Iron Systems

Landolt-Brnstein Numerical Data and Functional Relationships in Science and Technology New Series / Editor in Chief: W. Martienssen Group IV: Physical Chemistry Volume 11

Ternary Alloy Systems Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT Subvolume D Iron Systems Part 5 Selected Systems from Fe-N-V to Fe-Ti-Zr Editors G. Effenberg and S. Ilyenko Authors Materials Science and International Team, MSIT

ISSN 1615-2018 (Physical Chemistry) ISBN 978-3-540-70885-8 Springer Berlin Heidelberg New York Library of Congress Cataloging in Publication Data Zahlenwerte und Funktionen aus Naturwissenschaften und Technik, Neue Serie Editor in Chief: W. Martienssen Vol. IV/11D5: Editors: G. Effenberg, S. Ilyenko At head of title: Landolt-Brnstein. Added t.p.: Numerical data and functional relationships in science and technology. Tables chiefly in English. Intended to supersede the Physikalisch-chemische Tabellen by H. Landolt and R. Brnstein of which the 6th ed. began publication in 1950 under title: Zahlenwerte und Funktionen aus Physik, Chemie, Astronomie, Geophysik und Technik. Vols. published after v. 1 of group I have imprint: Berlin, New York, Springer-Verlag Includes bibliographies. 1. Physics--Tables. 2. Chemistry--Tables. 3. Engineering--Tables. I. Brnstein, R. (Richard), 1852-1913. II. Landolt, H. (Hans), 1831-1910. III. Physikalisch-chemische Tabellen. IV. Title: Numerical data and functional relationships in science and technology. QC61.23 502'.12 62-53136 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in other ways, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution act under German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com Springer-Verlag Berlin Heidelberg 2009 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Product Liability: The data and other information in this handbook have been carefully extracted and evaluated by experts from the original literature. Furthermore, they have been checked for correctness by authors and the editorial staff before printing. Nevertheless, the publisher can give no guarantee for the correctness of the data and information provided. In any individual case of application, the respective user must check the correctness by consulting other relevant sources of information. Cover layout: Erich Kirchner, Heidelberg Typesetting: Materials Science International Services GmbH, Stuttgart Printing and Binding: AZ Druck, Kempten/Allgu SPIN: 1221 0152 63/3020 - 5 4 3 2 1 0 Printed on acid-free paper

Editors: Gnter Effenberg Svitlana Ilyenko Associate Editor: Oleksandr Dovbenko MSI, Materials Science International Services GmbH Postfach 800749, D-70507, Stuttgart, Germany http://www.matport.com Authors: Materials Science International Team, MSIT The present series of books results from collaborative evaluation programs performed by MSI and authored by MSIT. In this program data and knowledge are contributed by many individuals and accumulated over almost twenty years, now. The content of this volume is a subset of the ongoing MSIT Evaluation Programs. Authors of this volume are:

Nataliya Bochvar, Moscow, Russia Marina

Bulanova, Kyiv, Ukraine Gabriele

Cacciamani, Genova, Italy Hailin Chen,

Changsha, China Gautam Ghosh, Evanston,

USA Lesley Cornish, Randburg, South

Africa Damian M. Cupid, Freiberg, Germany

Yong Du, Changsha, China Olga

Fabrichnaya, Freiberg, Germany Yulia

Fartushna, Kyiv, Ukraine Baiyun Huang,

Changsha, China Volodymyr Ivanchenko,

Kyiv, Ukraine Jozefien De Keyzer, Heverlee,

Belgium Natalia Kolchugina, Moscow,

Russia Kostyantyn Korniyenko, Kyiv,

Ukraine Artem Kozlov, Clausthal-Zellerfeld,

Germany Viktor Kuznetsov, Moscow, Russia

Shuhong Liu, Changsha, China

Hans Leo Lukas, Stuttgart, Germany

Pankaj Nerikar, Gainesville, USA Pierre

Perrot, Lille, France Tatiana Pryadko,

Kyiv, Ukraine Peter Rogl, Vienna, Austria

Lazar Rokhlin, Moscow, Russia Hans

Jrgen Seifert, Freiberg, Germany Elena

Semenova, Kyiv, Ukraine Weihua Sun,

Changsha, China Jean-Claude Tedenac,

Montpellier, France Vasyl Tomashik,

Kyiv, Ukraine Lyudmilla Tretyachenko,

Kyiv, Ukraine Tamara Velikanova, Kyiv,

Ukraine Andy Watson, Leeds, U.K. Wei

Xiong, Changsha, China Honghui Xu,

Changsha, China Chao Zhang, Changsha,

China Lijun Zhang, Changsha, China

Weiwei Zhang, Changsha, China

Institutions The content of this volume is produced by MSI, Materials Science International Services GmbH and the international team of materials scientists, MSIT. Contributions to this volume have been made from the following institutions:

The Baikov Institute of Metallurgy, Academy of Sciences, Moscow, Russia

Central South University, Research Institute of Powder Metallurgy, State Key Laboratory for Powder Metallurgy, Changsha, China

I.M. Frantsevich Institute for Problems of Materials Science, National Academy of Sciences, Kyiv, Ukraine

Institute for Semiconductor Physics, National Academy of Sciences, Kyiv, Ukraine

Katholieke Universiteit Leuven, Department Metaalkunde en Toegepaste Materiaalkunde, Heverlee, Belgium

G.V. Kurdyumov Institute for Metal Physics, National Academy of Sciences, Kyiv, Ukraine

Max-Planck-Institut fr Metallforschung, Institut fr Werkstoffwissenschaft, Pulvermetallurgisches Laboratorium, Stuttgart, Germany

Moscow State University, Department of General Chemistry, Moscow, Russia

Northwestern University, Department of Materials Science and Engineering, Evanston, USA

School of Chemical and Metallurgical Engineering, The University of the Witwatersrand, DST/NRF Centre of Excellence for Strong Material, South Afrika

Technische Universitt Bergakademie Freiberg, Institut fr Werkstoffwissenschaft, Freiberg, Germany

Technische Universitt Clausthal, Metallurgisches Zentrum, Clausthal-Zellerfeld, Germany

Universita di Genova, Dipartimento di Chimica, Genova, Italy

Universitt Wien, Institut fr Physikalische Chemie, Wien, Austria

Universite de Lille I, Laboratoire de Mtallurgie Physique, Villeneuve dASCQ, France

Universite de Montpellier II, Laboratorie de Physico-chimie de la Materiere Montpellier, France

University of Florida, Department of Materials Science and Engineering, Gainesville, USA

University of Leeds, Department of Materials, School of Process, Environmental and Materials Engineering, Leeds, UK

Preface The sub-series Ternary Alloy Systems of the Landolt-Brnstein New Series provides reliable and

comprehensive descriptions of the materials constitution, based on critical intellectual evaluations of all data available at the time and it critically weights the different findings, also with respect to their compatibility with todays edge binary phase diagrams. Selected are ternary systems of importance to alloy development and systems which gained in the recent years otherwise scientific interest. In one ternary materials system, however, one may find alloys for various applications, depending on the chosen composition.

Reliable phase diagrams provide scientists and engineers with basic information of eminent importance for fundamental research and for the development and optimization of materials. So collections of such diagrams are extremely useful, if the data on which they are based have been subjected to critical evaluation, like in these volumes. Critical evaluation means: there where contradictory information is published data and conclusions are being analyzed, broken down to the firm facts and re-interpreted in the light of all present knowledge. Depending on the information available this can be a very difficult task to achieve. Critical evaluations establish descriptions of reliably known phase configurations and related data.

The evaluations are performed by MSIT, Materials Science International Team, a group of scientists working together since 1984. Within this team skilled expertise is available for a broad range of methods, materials and applications. This joint competence is employed in the critical evaluation of the often conflicting literature data. Particularly helpful in this are targeted thermodynamic and atomistic calculations for individual equilibria, driving forces or complete phase diagram sections.

Conclusions on phase equilibria may be drawn from direct observations e.g. by microscope, from monitoring caloric or thermal effects or measuring properties such as electric resistivity, electro-magnetic or mechanical properties. Other examples of useful methods in materials chemistry are mass-spectrometry, thermo-gravimetry, measurement of electro-motive forces, X-ray and microprobe analyses. In each published case the applicability of the chosen method has to be validated, the way of actually performing the experiment or computer modeling has to be validated as well and the interpretation of the results with regard to the materials chemistry has to be verified. Therefore insight in materials constitution and phase reactions is gained from many distinctly different types of experiments, calculation and observations. Intellectual evaluations which interpret all data simultaneously reveal the chemistry of the materials system best.

An additional degree of complexity is introduced by the material itself, as the state of the material under test depends heavily on its history, in particular on the way of homogenization, thermal and mechanical treatments. All this is taken into account in an MSIT expert evaluation.

To include binary data in the ternary evaluation is mandatory. Each of the three-dimensional ternary phase diagrams has edge binary systems as boundary planes; their data have to match the ternary data smoothly. At the same time each of the edge binary systems A-B is a boundary plane for many other ternary A-B-X systems. Therefore combining systematically binary and ternary evaluations increases confidence and reliability in both ternary and binary phase diagrams. This has started systematically for the first time here, by the MSIT Evaluation Programs applied to the Landolt-Brnstein New Series. The degree of success, however, depends on both the nature of materials and scientists!

The multitude of correlated or inter-dependant data requires special care. Within MSIT an evaluation routine has been established that proceeds knowledge driven and applies both, human based expertise and electronically formatted data and software tools. MSIT internal discussions take place in almost all evaluation works and on many different specific questions the competence of a team is added to the work of individual authors. In some cases the authors of earlier published work contributed to the knowledge

base by making their original data records available for re-interpretation. All evaluation reports published here have undergone a thorough review process in which the reviewers had access to all the original data.

In publishing we have adopted a standard format that presents the reader with the data for each ternary system in a concise and consistent manner, as applied in the MSIT Workplace Phase Diagrams Online. The standard format and special features of the Landolt-Brnstein compendium are explained in the Introduction to the volume.

In spite of the skill and labor that have been put into this volume, it will not be faultless. All criticisms

and suggestions that can help us to improve our work are very welcome. Please contact us via [email protected]. We hope that this volume will prove to be as useful for the materials scientist and engineer as the other volumes of Landolt-Brnstein New Series and the previous works of MSIT have been. We hope that the Landolt Brnstein Sub-series, Ternary Alloy Systems will be well received by our colleagues in research and industry.

On behalf of the participating authors we want to thank all those who contributed their comments and

insight during the evaluation process. In particular we thank the reviewers - Pierre Perrot, Tamara Velikanova, Hans Leo Lukas, Marina Bulanova, Mikhail Turchanin, Nataliya Bochvar, Olga Fabrichnaya and Viktor Kuznetsov.

We all gratefully acknowledge the dedicated scientific desk editing by Oleksandra Berezhnytska, Mariya Saltykova and Oleksandr Rogovtsov.

Gnter Effenberg, Svitlana Ilyenko and Oleksandr Dovbenko Stuttgart, March 2008

Foreword

Can you imagine a world without iron and steel? No? I cant either. The story of mankind is intimately linked to the discovery and successful use of metals and their

alloys. Amongst them iron and steel - we could define steel as a generally hard, strong, durable, malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, Chromium, nickel, molybdenum, copper, tungsten, Cobalt, or silicon, depending on the desired alloy properties, and widely used as a structural material, have shaped our material world.

The story of iron takes us back to the period of the Hittite Empire around 1300 BC, when iron started

to replace bronze as the chief metal used for weapons and tools. Until today the story remains uncompleted and the social and economic impact of the iron and steel industry is now beyond imagination. In the year 2005 1.13 billion tons of crude steel were produced. Compared to 2004 this is an increase of 6.8%. That same year the steel production in China increased from 280.5 to almost 350 million tons. Concerning stainless steel: according to the International Stainless Steel Forum (ISSF), the global production forecast for 2006 now stands at 27.8 million metric tons of stainless crude steel, up 14.3% compared to 2005.

An English poem from the 19th century tells us

Gold is for the mistress Silver for the maid Copper for the craftsman Cunning at his trade Good said the baron Sitting in his hall But iron, cold iron Is master of them all

It is still actual and true. The list of different steel grades and related applications is impressive and still growing: low carbon

strip steels for automotive applications, low carbon structural steels, engineering steels, stainless steels, cast irons, and, more recently: dual phase steels, TRIP-steels, TWIP-steels, maraging steels,

The list of applications seems endless: a wide range of properties from corrosion resistance to high tensile strength is covered. These properties depend on the percentage of carbon, the alloying elements, and increasingly on the thermo-mechanical treatments that aim at optimizing the microstructure.

Yet many potential improvements remain unexplored, also due to the increasing complexity of the

new steel grades. For instance, a recently patent protected new die steel for hot deformation has the following composition specifications: C 0.46 0.58; Si 0.18 0.40; Mn 0.45 0.75, Cr 0.80 1.20; Ni 1.30 1.70; Mo 0.35 0.65; V 0.18 0.25; Al 0.01 0.04; Ti 0.002 0.04; B 0.001 0.003; Zr 0.02 0.04; Fe remaining.

Although many properties of steel are directly related to non-equilibrium states, it remains a fact that

the equilibrium state creates the reference frame for all changes that might occur in any material - and consequently would effect its properties in use - that is actually not in its thermodynamic equilibrium state. This is what these volumes in the Landolt-Brnstein series stand for: they have collected the most reliable data on the possible phase equilibria in ternary iron based alloys. Therefore this first volume of data, as well as the other ones in a series of four to appear, is of immeasurable value for metallurgists and materials engineers that improve the properties of existing steels and develop new and more complex steel grades. It is about materials, it is about quality of life.

The well-recognized quality label of MSIT, the Materials Science International Team, also applies to the present volume of the Landolt-Brnstein series. It should be available for every materials engineer, scientist and student.

Prof. Dr. ir. Patrick Wollants Chairman - Department of Metallurgy and Materials Engineering Katholieke Universiteit Leuven Belgium

Contents IV/11D5 Ternary Alloy Systems Phase Diagrams, Crystallographic and Thermodynamic Data Subvolume D Iron Systems Part 5 Selected Systems from Fe-N-V to Fe-Ti-Zr Introduction

Data Covered.......................................................................................................................................XIII General ................................................................................................................................................XIII Structure of a System Report ..............................................................................................................XIII

Introduction.................................................................................................................................XIII Binary Systems ...........................................................................................................................XIII Solid Phases ................................................................................................................................XIV Quasibinary Systems....................................................................................................................XV Invariant Equilibria ......................................................................................................................XV Liquidus, Solidus, Solvus Surfaces ............................................................................................. XV Isothermal Sections......................................................................................................................XV Temperature Composition Sections .........................................................................................XV Thermodynamics..........................................................................................................................XV Notes on Materials Properties and Applications.........................................................................XV Miscellaneous ..............................................................................................................................XV References ................................................................................................................................XVIII

General References .............................................................................................................................XIX Ternary Systems

FeNV (Iron Nitrogen Vanadium)..................................................................................................1 FeNaO (Iron Sodium Oxygen)....................................................................................................14 FeNbNi (Iron Niobium Nickel)...................................................................................................33 FeNbP (Iron Niobium Phosphorus) ............................................................................................43 FeNbSi (Iron Niobium Silicon)...................................................................................................55 FeNbZr (Iron Niobium Zirconium).............................................................................................69 FeNdSi (Iron Neodynium Silicon) ..............................................................................................82 FeNiP (Iron Nickel Phosphorus).................................................................................................96 FeNiS (Iron Nickel Sulfur)........................................................................................................113 FeNiSb (Iron Nickel Antimony) ...............................................................................................155 FeNiSi (Iron Nickel Silicon) .....................................................................................................171 FeNiTi (Iron Nickel Titanium)..................................................................................................188 FeNiV (Iron Nickel Vanadium) ................................................................................................212 FeNiW (Iron Nickel Tungsten) .................................................................................................225 FeNiZn (Iron Nickel Zinc) ........................................................................................................245 FeNiZr (Iron Nickel Zirconium) ...............................................................................................256

FeOPb (Iron Oxygen Lead).......................................................................................................268 FeOSi (Iron Oxygen Silicon) ....................................................................................................281 FeOU (Iron Oxygen Uranium)..................................................................................................322 FeOW (Iron Oxygen Tungsten) ................................................................................................330 FeOY (Iron Oxygen Yttrium) ...................................................................................................346 FeOZr (Iron Oxygen Zirconium) ..............................................................................................359 FePSi (Iron Phosphorus Silicon)...............................................................................................375 FeSTi (Iron Sulfur Titanium) ....................................................................................................393 FeSiTi (Iron Silicon Titanium)..................................................................................................410 FeSiV (Iron Silicon Vanadium) ................................................................................................428 FeSiZr (Iron Silicon Zirconium) ...............................................................................................447 FeSmTi (Iron Samarium Titanium) ..........................................................................................458 FeSnZr (Iron Tin Zirconium) ....................................................................................................480 FeTiV(Iron Titanium Vanadium)..............................................................................................493 FeTiY (Iron Titanium Yttrium).................................................................................................504 Fe-Ti-Zr (Iron Titanium Zirconium).............................................................................................518

IntroductionIron Systems: Phase Diagrams, Crystallographic and Thermodynamic Data

Data Covered

The series focuses on light metal ternary systems and includes phase equilibria of importance

for alloy development, processing or application, reporting on selected ternary systems of

importance to industrial light alloy development and systems which gained otherwise scien-

tific interest in the recent years.

General

The series provides consistent phase diagram descriptions for individual ternary systems.

The representation of the equilibria of ternary systems as a function of temperature results

in spacial diagrams whose sections and projections are generally published in the literature.

Phase equilibria are described in terms of liquidus, solidus and solvus projections, isother-

mal and quasibinary sections; data on invariant equilibria are generally given in the form

of tables.

The world literature is thoroughly and systematically searched back to the year 1900.

Then, the published data are critically evaluated by experts in materials science and

reviewed. Conflicting information is commented upon and errors and inconsistencies

removed wherever possible. It considers those, and only those data, which are firmly estab-

lished, comments on questionable findings and justifies re-interpretations made by the

authors of the evaluation reports.

In general, the approach used to discuss the phase relationships is to consider changes

in state and phase reactions which occur with decreasing temperature. This has influen-

ced the terminology employed and is reflected in the tables and the reaction schemes

presented.

The system reports present concise descriptions and hence do not repeat in the text facts

which can clearly be read from the diagrams. For most purposes the use of the compendium is

expected to be self-sufficient. However, a detailed bibliography of all cited references is given to

enable original sources of information to be studied if required.

Structure of a System Report

The constitutional description of an alloy system consists of text and a table/diagram section

which are separated by the bibliography referring to the original literature (see Fig. 1). The

tables and diagrams carry the essential constitutional information and are commented on in

the text if necessary.

Where published data allow, the following sections are provided in each report:

Introduction 1 1

LandoltBornsteinNew Series IV/11D5

DOI: 10.1007/978-3-540-70890-2_1

Springer 2009MSIT1

Introduction

The opening text reviews briefly the status of knowledge published on the system and outlines

the experimental methods that have been applied. Furthermore, attention may be drawn to

questions which are still open or to cases where conclusions from the evaluation work

modified the published phase diagram.

Binary Systems

Where binary systems are accepted from standard compilations reference is made to these

compilations. In other cases the accepted binary phase diagrams are reproduced for the

convenience of the reader. The selection of the binary systems used as a basis for the evaluation

of the ternary system was at the discretion of the assessor.

. Fig. 1Structure of a system report

2 1 Introduction

DOI: 10.1007/978-3-540-70890-2_1 LandoltBornstein Springer 2009 New Series IV/11D5MSIT1

Solid Phases

The tabular listing of solid phases incorporates knowledge of the phases which is necessary or

helpful for understanding the text and diagrams. Throughout a system report a unique phase

name and abbreviation is allocated to each phase.

Phases with the same formulae but different space lattices (e.g. allotropic transformation)

are distinguished by:

small letters (h), high temperature modification (h2 > h1)(r), room temperature modification

(1), low temperature modification (l1 > l2)

Greek letters, e.g., , Roman numerals, e.g., (I) and (II) for different pressure modifications.

In the table Solid Phases ternary phases are denoted by * and different phases are

separated by horizontal lines.

Quasibinary Systems

Quasibinary (pseudobinary) sections describe equilibria and can be read in the same way as

binary diagrams. The notation used in quasibinary systems is the same as that of vertical

sections, which are reported under Temperature Composition Sections.

Invariant Equilibria

The invariant equilibria of a system are listed in the table Invariant Equilibria and, where

possible, are described by a constitutional Reaction Scheme (Fig. 2).

The sequential numbering of invariant equilibria increases with decreasing temperature,

one numbering for all binaries together and one for the ternary system.

Equilibria notations are used to indicate the reactions by which phases will be

decomposed (e- and E-type reactions)

formed (p- and P-type reactions)

transformed (U-type reactions)

For transition reactions the letter U (Ubergangsreaktion) is used in order to reserve the

letter T to denote temperature. The letters d and D indicate degenerate equilibria which do not

allow a distinction according to the above classes.

Liquidus, Solidus, Solvus Surfaces

The phase equilibria are commonly shown in triangular coordinates which allow a reading of

the concentration of the constituents in at.%. In some cases mass% scaling is used for better

data readability (see Figs. 3 and 4).

Introduction 1 3


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Springer 2009MSIT1

.Fig.2

Typicalreactionscheme

4 1 Introduction


In the polythermal projection of the liquidus surface, monovariant liquidus grooves

separate phase regions of primary crystallization and, where available, isothermal lines con-

tour the liquidus surface (see Fig. 3).

Isothermal Sections

Phase equilibria at constant temperatures are plotted in the form of isothermal sections (see

Fig. 4).

Temperature Composition Sections

Non-quasibinary T-x sections (or vertical sections, isopleths, polythermal sections) show the

phase fields where generally the tie lines are not in the same plane as the section. The notation

employed for the latter (see Fig. 5) is the same as that used for binary and quasibinary phase

diagrams.

. Fig. 3Hypothetical liqudus surface showing notation employed

Introduction 1 5


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Thermodynamics

Experimental ternary data are reported in some system reports and reference to thermody-

namic modeling is made.

Notes on Materials Properties and Applications

Noteworthy physical and chemical materials properties and application areas are briefly

reported if they were given in the original constitutional and phase diagram literature.

Miscellaneous

In this section noteworthy features are reported which are not described in preceding para-

graphs. These include graphical data not covered by the general report format, such as lattice

spacing composition data, p-T-x diagrams, etc.

. Fig. 4Hypotheticcal isothermal section showing notation employed

6 1 Introduction


References

The publications which form the bases of the assessments are listed in the following manner:

[1974Hay] Hayashi, M., Azakami, T., Kamed, M., Effects of Third Elements on the

Activity of Lead in Liquid Copper Base Alloys (in Japanese), Nippon Kogyo Kaishi, 90, 51-

56 (1974) (Experimental, Thermodyn., 16)

This paper, for example, whose title is given in English, is actually written in Japanese. It

was published in 1974 on pages 51- 56, volume 90 of Nippon Kogyo Kaishi, the Journal of the

Mining and Metallurgical Institute of Japan. It reports on experimental work that leads to

thermodynamic data and it refers to 16 cross-references.

Additional conventions used in citing are:

# to indicate the source of accepted phase diagrams

* to indicate key papers that significantly contributed to the understanding of the system.

Standard reference works given in the list General References are cited using their

abbreviations and are not included in the reference list of each individual system.

. Fig. 5Hypothetical vertical section showing notation employed

Introduction 1 7


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Springer 2009MSIT1

General References

[C.A.] Chemical Abstracts - pathways to published research in the worlds journal and patent literature -

http://www.cas.org/

[Curr.Cont.] Current Contents - bibliographic multidisciplinary current awareness Web resource - http://www.

isinet.com/products/cap/ccc/

[E] Elliott, R.P., Constitution of Binary Alloys, First Supplement, McGraw-Hill, New York (1965)

[G] Gmelin Handbook of Inorganic Chemistry, 8th ed., Springer-Verlag, Berlin

[H] Hansen, M. and Anderko, K., Constitution of Binary Alloys, McGraw-Hill, New York (1958)

[L-B] Landolt-Boernstein, Numerical Data and Functional Relationships in Science and Technology (New

Series). Group 3 (Crystal and Solid State Physics), Vol. 6, Eckerlin, P., Kandler, H. and Stegherr, A.,

Structure Data of Elements and Intermetallic Phases (1971); Vol. 7, Pies, W. and Weiss, A., Crystal

Structure of Inorganic Compounds, Part c, Key Elements: N, P, As, Sb, Bi, C (1979); Group 4:

Macroscopic and Technical Properties of Matter, Vol. 5, Predel, B., Phase Equilibria, Crystallographic

and Thermodynamic Data of Binary Alloys, Subvol. a: Ac-Au Au-Zr (1991); Springer-Verlag,

Berlin.

[Mas] Massalski, T.B. (Ed.), Binary Alloy Phase Diagrams, ASM, Metals Park, Ohio (1986)

[Mas2] Massalski, T.B. (Ed.), Binary Alloy Phase Diagrams, 2nd edition, ASM International, Metals Park,

Ohio (1990)

[P] Pearson, W.B., A Handbook of Lattice Spacings and Structures of Metals and Alloys, Pergamon Press,

New York, Vol. 1 (1958), Vol. 2 (1967)

[S] Shunk, F.A., Constitution of Binary Alloys, Second Supplement, McGraw-Hill, New York (1969)

[V-C] Villars, P. and Calvert, L.D., Pearsons Handbook of Crystallographic Data for Intermetallic Phases,

ASM, Metals Park, Ohio (1985)

[V-C2] Villars, P. and Calvert, L.D., Pearsons Handbook of Crystallographic Data for Intermetallic Phases,

2nd edition, ASM, Metals Park, Ohio (1991)

8 1 Introduction


Index of Alloy SystemsIron Systems: Phase Diagrams, Crystallographic and Thermodynamic Data

Index of Ternary Iron Alloy Systems Fe-N-V to Fe-Ti-Zr

FeNV (Iron Nitrogen Vanadium)

FeNaO (Iron Sodium Oxygen)

FeNbNi (Iron Niobium Nickel)

FeNbP (Iron Niobium Phosphorus)

FeNbSi (Iron Niobium Silicon)

FeNbZr (Iron Niobium Zirconium)

FeNdSi (Iron Neodynium Silicon)

FeNiP (Iron Nickel Phosphorus)

FeNiS (Iron Nickel Sulfur)

FeNiSb (Iron Nickel Antimony)

FeNiSi (Iron Nickel Silicon)

FeNiTi (Iron Nickel Titanium)

FeNiV (Iron Nickel Vanadium)

FeNiW (Iron Nickel Tungsten)

FeNiZn (Iron Nickel Zinc)

FeNiZr (Iron Nickel Zirconium)

FeOPb (Iron Oxygen Lead)

FeOSi (Iron Oxygen Silicon)

FeOU (Iron Oxygen Uranium)

FeOW (Iron Oxygen Tungsten)

FeOY (Iron Oxygen Yttrium)

FeOZr (Iron Oxygen Zirconium)

FePSi (Iron Phosphorus Silicon)

FeSTi (Iron Sulfur Titanium)

FeSiTi (Iron Silicon Titanium)

FeSiV (Iron Silicon Vanadium)

FeSiZr (Iron Silicon Zirconium)

FeSmTi (Iron Samarium Titanium)

FeSnZr (Iron Tin Zirconium)

FeTiV (Iron Titanium Vanadium)

FeTiY (Iron Titanium Yttrium)

Fe-Ti-Zr (Iron Titanium Zirconium)

Index of Alloy Systems 2 1


DOI: 10.1007/978-3-540-70890-2_2

Springer 2009MSIT1

Iron Nitrogen VanadiumIron Systems: Phase Diagrams, Crystallographic and Thermodynamic Data

Pierre Perrot

Introduction

Vanadium has a strong affinity for N and forms fine nitrides and carbonitrides in steels which

improve their strength and the toughness by pinning the grain growth to a considerable extent.

Experimental investigations on phase equilibria and thermodynamics, mainly related to the

nitrogen solubilities in liquid, and phases are gathered in Table 1. Few experimentalinformation exists in the ternary phase diagram [1978ElS] and Calphad assessments

[1991Oht2] are useful to get an insight to the equilibria between phases. A review on the

phase equilibria in the Fe-N-V system may be found in [1983Rag, 1984Rag, 1987Rag1,

1993Rag]. A Calphad assessment of the Fe-N-V system has been carried out by [1991Oht2].

Binary Systems

The Fe-V has been carefully reviewed by [1984Smi] and the thermodynamic assessment

proposed by [1991Kum] reproduces well the accepted diagram. According to new experimen-

tal works [2005Ust1, 2005Ust2], the phase would be unstable and a phase separation wouldbe observed below 650C. A further confirmation is needed to accept this new version of the

Fe-V diagram at low temperatures. The Fe-N phase diagram in the solid state is accepted from

the review of [1987Wri]. The Calphad assessment carried out by [1991Fri] and justified by the

model proposed by [1994Fer] gives an insight on the phase equilibria under high nitrogen

pressures. The N-V phase diagram in the solid state given by [Mas2] is reproduced from the

extensive review of [1989Car]. A Calphad assessment of the N-V system has been carried out

by [1991Oht1], then updated by [1997Du]. These assessments do not take into account the

V32N26 phase but agree to propose for the nitrides V2N and VN incongruent melting pointsunder 0.1 MPa N2 higher than those accepted by [Mas2]. The N-V diagram accepted in the

present report is that proposed by [1997Du].

Solid Phases

The solid phases are shown in Table 2. Three vanadium nitrides are stable. The most stable,

easily precipitated in steels is VN which presents a large non stoichiometry and may be

obtained under very low nitrogen potential. The hexagonal subnitride V2N, exhibits a

structure Fe3N like, but no solid solutions have been reported between these two phases.The iron nitride Fe4N is characterized by a high saturation magnetization and a lowcoercitivity and many efforts has been devoted to enhance its magnetic properties by metallic

substitution. Many metastable phases of the type Fe4xMxN have been prepared by mechanical

alloying, but no report seems to exist in which M stands for V. Despite this, self-consistent

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band structure calculations were performed for the V4N, V3FeN and VFe3N materials

[2006San]. They were found non magnetic and their crystal structure calculated at 752.9,

742.7 and 704.9 pm respectively, whereas twice lattice parameter for Fe4N gives 757.4 pm.

[2006San] reports for Fe4N a lattice parameter of 717.1 pm.

Isothermal Sections

The nitrogen solubility in liquid (Fe,V) alloys has been considerably investigated as shown in

Table 1, and was shown to increase with the V content, but the increase of the nitrogen

dissolved in the melt may be limited by the precipitation of VN for high V content of the alloy.

A useful empirical expression of the N solubility in liquid alloys at 1580C has been proposed

by [1963Kor]:

mass%N 0:043 0:0185 mass%V 0:00113 mass%V2< 6mass%VThe precipitation is observed when the solubility product (mass% V)(mass% N) is

reached. As liquid Fe can dissolve a large amount of V before precipitating as VN, the

solubility product cannot be precisely represented by the product of concentrations, but by

the product of the activities. Another problem concerns the composition of the VN nitride in

equilibrium with the liquid alloy. [1965Eva] considers that its composition is V1.41N whereas

most authors consider that it is VN. The lattice parameter measurement carried out by

[1987Mor] identifies the precipitated nitride as VN. It is probable that VN in equilibrium

with iron rich (Fe,V) alloys and that the V content of the nitride increases with that of the

alloy. According to [1963ElT], a Fe-8V (mass%) alloy precipitates VN once the N content

reaches 0.20 mass% at 1600C under 8 kPa of N2 pressure; a Fe-15V (mass%) alloy preci-

pitates VN once the N content reaches 0.27 mass% at 1600C under 77 kPa of N2 pressure.

The nitrogen solubility in liquid alloys seems independent on the temperature for the Fe-1V

(mass%) [1958Kas]. Below 1 mass% V in the alloy, it decreases when the temperature raises,

above 1 mass% V in the alloy, it increases with the temperature [1987Mor].

The solubility of nitrogen generated by H2-NH3 atmospheres at 400-600C on (Fe,V)alloys up to 0.05 mass% V [1955Tur] seems independent on the V content of the alloy. The

formation of VN is not observed at nitrogen potentials under which iron nitrides are not

formed. The V content of the alloy was probably too small and the nitrogen solubility

measured in and alloys [1958Fou, 1962Kor2] up to 1 mass% V was shown to increasewith the V concentration.

The solubility product of VN in and alloys has been evaluated by [1962Kor2] andaccepted by [2004Ked] to model the nitrogen diffusion profile during nitriding:

In a Fe;V alloys : log10mass%Vmass%N 2:45 7830=TIn g Fe;V alloys : log10mass%Vmass%N 2:27 7070=T

At 700C, the solubility product of VN in (Fe) is 2.5 106 which is in agreement withthe formation of VN observed by [1973Gul] in an alloy Fe-0.18 mass% V-0.04 mass% N. At

1350C, the solubility product of VN in (Fe) is 0.0082 which is in agreement with theobservation of [1973Gul] that pure iron may absorb up to 0.2 mass% VN. The solubility

product of VN in (Fe) has been measured at 5.3 106 and 1.7 105 at 700 and 800C,respectively, by [1973Koy] using internal friction measurements. The N solubility under

2 3 FeNV


0.1 MPa of N2 pressure in iron rich alloys (< 2 mass% V) at 1200C ( and solid alloys) and1600C (liquid alloy) is shown in Fig. 1.

Due to the lack of experimental information with the exception of the nitrogen solubilities

in , and liquid phases, the isothermal sections have been calculated. The isothermal sectionsat 1200 and 1600C, presented in Figs. 2 and 3 respectively, are mainly from [1991Oht2]

slightly modified to take into account the non stoichiometry of the binary compounds and the

solubility of N into (Fe) according to the accepted Fe-N diagram. Although a partialsolubility is probable, it has never been measured.


The vertical section through the Fe-N-V diagram at 3 mass% V calculated by [1991Oht2], is

shown in Fig. 4. The original figure has been slightly modified in order to remove the very

improbable shrinkage present at 900 and 1400C in the three-phase field ++VN. It looks likethe binary Fe-N phase diagram calculated by [1991Fri] with an enlarged domain. Theisobaric curves have not been calculated, but the nitrogen potentials (0.1 MPa at 1600C

and 0.044 mass% N) increase strongly with the N content. Below 800C, they may be obtained

with H2-NH3 atmospheres, but above this temperature, there is no known mean to impose

such high nitrogen potentials. The vertical section along the Fe-VN path (< 1 mass% VN) is

shown in Fig. 5. The easy precipitation of VN in the and solid phases appears clearly inboth Figs. 4 and 5. In the liquid phase at 1600C, VN precipitates under 0.1 MPa N2 for a V

content in the alloys higher than 10 mass%.

Thermodynamics

The interaction coefficient between N and V in liquid iron calculated by [1960Mae] from

solubility measurements was found eN(V) = ( log10 fN / mass% V) = 0.11 at 1600-1750C,

where fN = (mass% N in pure Fe) / (mass% N in the alloy). Such a value, is in a very good

agreement with that calculated from the data of [1958Kas] (0.095 at 1600C) and with

the later measurements carried out by [1960Peh] (0.10 at 1606C), [1961Rao] (0.094 at

1700C), [1962Kor1] (0.106 at 1580C), [1963ElT] (0.094 at 1600C), [1965Eva] (0.093

at 1600C and 0.079 at 1750C), [1975Pom] (0.12 at 1600C, 0.099 at 1800C and 0.093 at

1900C), [1981Wad] (0.10 at 1600C, 0.087 at 1700C and 0.076 at 1800C) and [1987Mor]

(0.107 at 1600C). [1963Kor] proposes a more precise expression of the interaction para-

meter at 1580C, which may be used up to 6 mass% V in the alloy: eN(V) = 0.159 + 0.016

(mass% V), which agrees with the preceding values. [1963ElT] proposes, in the temperature

range 1600-1740C the following expression: eN(V) = 0.075 317 / T, which is more represen-

tative in a wide temperature range than more recent expressions [1981Wad, 1987Mor]. This

expression, extrapolated at 2200C leads to eN(V) = 0.052 which agrees well with the

experimental value of 0.062 obtained by [1968Uda] at 2140-2240C by arc melting or

levitation melting under N2 atmospheres and with the experimental value of 0.05 obtained

by [1969Wad] with the same method.

The interaction coefficient may be expressed in mole fractions. At 1600C [1966Sch,

1987Mor]: N(V) = ( ln N / xV) = 20 at 1600C, where N = (xN pure Fe / xN in the

alloy). For higher V content of the alloy, the preceding primary interaction coefficients cannot

be used and it is necessary to define secondary and sometimes ternary interaction coefficients

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and to take into account the auto-interaction coefficient [2001Hut]. Indeed, under high

nitrogen pressure (> 0.1 MPa) and high V content (> 6 mass%), N has a strong effect on its

own activity coefficient. So, [2003Hut] describes the nitrogen solubility in (Fe,V) alloys up to

45 mass% V between 1800 and 2000C by using interaction coefficients of high order.

The interaction coefficients between N and V in and iron have been calculated by[1958Fou] from solubility measurements and found eN

(V) = 2.2, 1.0, 0.47, 0.33 and 0.18

at 750, 850, 950, 1050 and 1200C respectively. The slope of the curve does not seem present a

break at the / transition of the alloy. These values are confirmed by the measurements of[1962Kor2] which proposes eN

(V) = 0.4 at 1000C.

A general discussion on the interaction parameters in alloys may be found in [1966Sch].

A method of calculation based on equivalent carbon concentration was developed by

[1967Sch].

Table 3 presents the Gibbs energy of dissolution of N2 in liquid Fe-V alloys measured by

[1975Pom]. The enthalpy of dissolution of N2, positive for pure Fe, decreases when the V

content in the alloy increases, passes through zero for Fe-1V (mass%) then becomes more and

more negative. The nitrogen solubility in the Fe-1V (mass%) does not change with tempera-

ture, an observation already made by [1958Kas].

Notes on Materials Properties and Applications

Main experimental investigations are gathered in Table 4. Vanadium, which in the liquid state

absorbs readily nitrogen, greatly increases its solubility in Fe base alloys without VN precipi-

tation. By solidification, these alloys precipitate VN, leading to a structural hardening of the

steel and an improvement of its tribological behavior, mechanical properties, especially under

fatigue loading and of its corrosion resistance. The easy absorption of N by (Fe,V) liquid alloys

without VN precipitation allows the preparation of HNS (High Nitrogen Steels, that are steels

with more than 0.5 mass% N) by using high nitrogen pressures. For instance, a Fe-12 mass%

Valloy at 1700C may absorb 0.503, 0.674, 0.847 and 1.400 mass% N under nitrogen pressures

of 0.372, 0.743, 1.86 and 2.27 MPa, respectively [2003Siw].

Vanadium and nitrogen cosegregation towards the surface has been observed on a Fe-3

mass% V annealed at 570-740C under a N2-H2 atmosphere (1 to 10 Pa N2) leading to a

nitrogen content of 4 to 30 ppm inside the alloy [1995Ueb]. N segregation gives a two-

dimensional surface compound whose composition is VN1.0 0.1. VN precipitates were also

observed by nitriding Fe-V alloys up to 3.3 at.% in a salt bath at 570C [2003Gou]. VN

precipitates as platelets, forming tweed structures, typical of a Guinier-Preston zone, due to a

tetragonal distortion of the matrix.

Miscellaneous

The nitrogen diffusion was investigated in the solid [1966Koe, 1973Bel, 1977Bor] and liquid

[1981Ers] alloys. In solid and liquid alloys, V has for effect to decrease the nitrogen diffusion

coefficient and to increase the activation energy of the diffusion. In pure Fe, the N diffusioncoefficient is given by:

DN / cm2s1 = 0.005 exp(9260 / T), which corresponds to an activation energy of

77 kJmol1. In a V added with 0.75 mass% V, the N diffusion coefficient is given by:

4 3 FeNV


DN / cm2s1 = 0.0066 exp(13 300 / T), which corresponds to an activation energy of

110.9 kJmol1. Using the positron annihilation technique, [1990Wan] observes, on dilute

Fe-V alloys (0.29 mass% V) annealed at 500C under a 80H2-20NH3 atmosphere, the forma-

tion of VN clusters inside the Fe matrix. As V does not diffuse in Fe at so low temperature, it is

clear that N greatly enhances the V diffusion in Fe.

The nitrogen diffusion profile during the nitriding of a Fe-Valloy (0.5 and 1.0 mass% V) at

550-580C has been modeled by [2000Gou, 2004Ked]. The increase of the V content affects the

thickness of the nitrided layer, due to the formation of VN precipitates. After 70 h of diffusion

at 570C, the nitrided layer is 72 m thick for pure Fe and 215 m thick for Fe added with1 mass% V. [2005Kam] presents a trapping model and points out that a realistic diffusion

model must take into account both precipitation and trapping.

The morphologies of the nitrided layers at 580C under H2-NH3 atmospheres were

compared by [2005Hos] on two Fe-V alloys (2 and 4 mass% V). The difference observed

was caused by a discontinuous coarsening reaction occurring on the Fe-4%V alloy, caused by

an uptake of excess nitrogen in the nitrided zone. It was observed, on the Fe-2V (mass%)

[2006Hos] that the hydrogen uptake was larger than that necessary to precipitate Vas VN and

to saturate the ferrite matrix. Three types of nitrogen were recognized: nitrogen in the

stoichiometric VN, nitrogen adsorbed at the (Fe)/VN interface and nitrogen dissolvedinterstitially in the ferrite matrix. The excess nitrogen uptake is partly due to the immobile

nitrogen at the interface (Fe)/VN and partly due to the mobile nitrogen supersaturated in the(Fe) matrix. The supersaturation of the ferrite is due to the misfit stress field surrounding thenitride precipitates. The excess nitrogen dissolved at the interface (Fe)/VN was shown todecrease with increasing temperature [2007Hos].

The presence of V in liquid Fe at 1600C was shown to increase the rate of dissolution of

N2 by comparison with pure Fe [1995Ono].

. Table 1Investigations of the Fe-N-V Phase Relations, Structures and Thermodynamics

Reference Method/Experimental Technique

Temperature/Composition/Phase Range

Studied

[1955Tur] Nitrogen solubility in (Fe,V) alloys,sampling method

500-600C, < 0.05 mass% V, H2-NH3atmospheres

[1958Fou] Nitrogen solubility in and (Fe,V)alloys, Sieverts method

750-120C, < 0.5 mass% V, < 0.1 MPa of

N2 pressures

[1958Kas] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1600C, < 10 mass% V, < 0.1 MPa of N2pressure

[1960Mae] Nitrogen solubility in liquid (Fe,V) alloys,

Sampling method

1600-1750C, < 8 mass% V, 0.1 MPa of N2pressure

[1960Peh] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1606C, < 12 mass% V, < 0.1 MPa of N2pressure

[1961Rao] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1687-1760C, < 20 mass% V, < 0.1 MPa of

N2 pressure

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. Table 1 (continued)

Reference Method/Experimental Technique

Temperature/Composition/Phase Range

Studied

[1962Kor1] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1580C, < 12 mass% V, 0.1 MPa of N2pressure

[1962Kor2] VN solubility in (Fe,V) alloys, Sievertsmethod

900-1300C, < 1 mass% V, 0.1 MPa of N2pressure

[1963ElT] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1600-1750C, < 20 mass% V, < 0.1 MPa of

N2 pressure

[1963Kor] VN solubility in liquid (Fe,V) alloys,

Sieverts method

900-1300C, < 1 mass% V, 0.1 MPa of

N2 pressure

[1965Eva] Nitrogen solubility in liquid (Fe,V) alloys,

Sieverts method

1600-1750C, < 16 mass% V, 0.1 MPa of

N2 pressure

[1968Uda] Nitrogen solubility in liquid (Fe,V) arc-

and levitation melted alloys

2140-2240C, < 6 mass% V, < 0.1 MPa of

N2 pressure

[1969Wad] Nitrogen solubility in liquid (Fe,V)

levitation melted alloys

1800-2200C, < 50 mass% V, < 0.1 MPa of

N2 pressure

[1973Gul] VN solubility in and Fe, phase analysisby electron microscopy

700-1350C, < 0.18 mass% V,

< 0.04 mass% V

[1973Koy] VN solubility in Fe, internal friction,chemical analysis

700-800C, < 0.12 mass% V,

< 0.024 mass% N

[1975Pom] Nitrogen solubility in liquid (Fe,V)

melted by plasma

1790-2150C, < 11 mass% V, < 0.4 mass% N,

< 0.1 MPa of N2 pressure

[1978ElS] XRD, Metallography, Electron Probe

Microanalysis (EPMA)

1100-1200C, Fe-N-V constitution diagram

(~1 mPa N2)

[1981Wad] Nitrogen solubility in liquid (Fe,V)

Sieverts method

1600-1800C, < 15 mass% V, < 0.1 MPa of

N2 pressure

[1987Mor] Solubility if VN in liquid (Fe,V), XRD,

chemical analysis

1600-1700C, < 25 mass% V, < 0.35 mass%

N, < 0.1 MPa of N2 pressure

[2001Hut] Nitrogen solubility in liquid (Fe,V)

Levitation melted alloys

1900C, < 12.2 mass% V, 0.1 to 2.1 MPa of

N2 pressure

[2003Hut] Nitrogen solubility in liquid (Fe,V)


1800-2000C, < 45 mass% V, 1 kPa to 2.5

MPa of N2 pressure

[2003Siw] Nitrogen solubility in liquid (Fe,V)


1700C, < 12 mass% V, < 0.4 MPa of N2pressure, < 1.4 mass% N

6 3 FeNV


. Table 2Crystallographic Data of Solid Phases

Phase/

Temperature

Range [C]

Pearson Symbol/

Space Group/

Prototype

Lattice Parameters

[pm] Comments/References

, (Fe,V,Fe) cI2(V) Im3m a = 302.40 at 25C [Mas2]< 1910 W dissolves 13 at.% N at 1959C

[1997Du]

(Fe) a = 293.15 [Mas2]1538 - 1394

(Fe) a = 286.65 pure Fe at 20C [Mas2]< 912 dissolves up to 0.4 at.% N at 590C

(Fe0.5V0.5) a = 292.0 [1984Smi]

(Fe) cF4 a = 364.67 at 915C [Mas2, V-C2]1394 - 912 Fm3m dissolves up to 10.3 at.% N at 650C

Cu [1987Wri] and 1.4 at.% V at 1150C

[1984Smi]

(Fe) hP2 a = 246.8 at 25C, 13 GPa [Mas2]P63/mmc c = 396.0 triple point -- at 8.4 GPa, 430C

Mg

, VFe tP30 29.6 to 60.1 at.% V< 1252 P42/mnm a = 886.5 at 29.6 at.% V [1984Smi]

CrFe c = 460.5a = 895.0 at 50 at.% V [1984Smi]

c = 462.0

a = 901.5 at 60 at.% V [1984Smi]

c = 464.2

Fe16N2 tI* a = 572 ordered fcc structure, metastable[1987Wri]I4/mmn c = 629

, Fe4N cP5 a = 378.7 19.4 to 20.6 at.% N. Ordered fccstructure [1987Rag2]< 680 Pm3m

Fe4N

, Fe3N hP10 15.8 to 33.2 at.% N [1987Rag2]< 580 P6322 a = 469.96 0.03 Fe3N at RT [1999Lei]

Fe3N c = 438.04 0.03

a = 471.8 Fe3N1.10 [2001Lei]c = 438.8 Lattice parameters decrease

slightly with decrease in nitrogen

content [2001Lei]

a = 479.1 Fe3N1.39 [2001Lei]

c = 441.9

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. Table 2 (continued)

Phase/

Temperature

Range [C]

Pearson Symbol/

Space Group/

Prototype

Lattice Parameters

[pm] Comments/References

Fe2N oP12 a = 551.2 at 25C [1987Rag2]< 500 Pbcn b = 482.0

Fe2N c = 441.6

V2N hP3 24.2 to 32.9 at.% N [1984Rag]< 2409 P63/mmc a = 283.68 to 284.08 [1984Rag]

(under 0.1 MPa N2) Fe3N c = 454.21 to 455.01

VN cF8 33 to 50 at.% N [Mas2]< 2119 Fm3m

(under 0.1 MPa N2) NaCl a = 406.62 at 42 at.% N [1984Rag]

< 3000

(under 1 GPa N2) a = 413.98 at 50 at.% N [1984Rag]

V32N26 tP* - 43 to 46 at.% N [Mas2]< 520 P42/nmc

-

. Table 3Thermodynamic Data of Reaction or Transformation

Reaction or Transformation

Temperature

[C]

Quantity, per mol of

atoms [J, mol, K] Comments

N2 {N} (in Liquid Fe) 2000 rH = + 5600 [1975Pom] N2 {N} (in Liquid Fe + 1 mass% V) 1790-2130 rG = 340 + 23.0 T [1975Pom] N2 {N} (in Liquid Fe + 2 mass% V) 1790-2110 rG = 7660 + 25.7 T [1975Pom] N2 {N} (in Liquid Fe + 5.2 mass% V) 1810-2110 rG = 28700 + 29.7 T [1975Pom] N2 {N} (in Liquid Fe + 7.4 mass% V) 1830-2150 rG = 42100 + 32.5 T [1975Pom] N2 {N} (in Liquid Fe + 11.1 mass% V) 1830-2150 rG = 61100 + 37.3 T [1975Pom]VN {V} + {N} (Ref: 1 mass% in liquid Fe) 1600-1700 rG = 167000 83.7 T [1987Mor]

8 3 FeNV


. Table 4Investigations of the Fe-N-V Materials Properties

Reference Method / Experimental Technique Type of Property

[1966Koe] Damping capacity, diffusion coefficient < 800C, < 4 mass% V, < 0.4 mass% N

[1973Bel] X-Ray and electron diffraction, MEB,

hardness measurements

400-700C, < 9 mass% V, diffusion layer

formation

[1977Bor] XRD, micrography, thickness and

hardness measurements

500-900C, < 15.6 mass% V, H2-NH3atmospheres, layer growth kinetics

[1977Kra] XRD, electron microscopy, crystal

parameters

< 800C, < 2 at.% V, < 3 at.% N, H2-NH3atmospheres, local atomic arrangements

[1981Ers] Diffusion coefficient of N in liquid alloys,

volumetric method

1600C, < 8 mass% V, 0.1 MPa of N2pressure

[1990Wan,

1993Wan]

Positron annihilation spectroscopy,

observation of VN clusters

500C, Fe + 0.29 mass% V, 80H2-20NH3atmosphere

[1995Ono] Isotopic exchange reaction 1600-1750C, 0.1 MPa of N2 pressure,

kinetics of dissolution

[1995Ueb] Auger Electron Spectroscopy (AES), low

energy electron diffraction

570-740C, Fe-3 mass% V-N (4 to 30 ppm

N), 1 to 10 Pa of N2 pressure,

[2003Gou] XRD, TEM, Electron Microprobe

Microanalysis (EPMA)

Fe-V (< 3.3 at.% V) nitridized at 570C in

a nitriding fused salt bath. VN formation.

[2005Hos] XRD, SEM, EPMA, hardness

measurements

580C, 2 and 4 mass% V, H2-NH3atmospheres, morphology


measurements

580C, 2 mass% V, H2-NH3 atmospheres,

excess N uptake


measurements

520-600C, 2 mass% V, 9H2-91NH3atmospheres, excess N uptake

FeNV 3 9


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. Fig. 1Fe-N-V. The Fe rich corner at 1200 and 1600C under 0.1 MPa of N2 pressure

10 3 FeNV


. Fig. 2Fe-N-V. Isothermal section at 1200C

FeNV 3 11


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. Fig. 3Fe-N-V. Isothermal section at 1600C

12 3 FeNV


. Fig. 4Fe-N-V. Partial vertical section at 3 mass% V

FeNV 3 13


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. Fig. 5Fe-N-V. Calculated Fe-VN partial vertical section

14 3 FeNV


References

[1955Tur] Turkdogan, E.T., Ignatowicz, S., Pearson, J., The Effect of Alloying Elements on the Solubility of

Nitrogen in Iron. II. The Solubility of Nitrogen in -Iron Containing up to 0.051% Vanadium, J. IronSteel Inst., 181, 227231 (1955) (Experimental, Phase Relations, 22)

[1958Fou] Fountain, R.W., Chipman, J., Solubility and Precipitation of Vanadium Nitride in - and -Iron,Trans. Met. Soc. AIME, 212, 737748 (1958) (Experimental, Phase Relations, Thermodyn., 29)

[1958Kas] Kashyap, V.C., Parlee, N., Solubility of Nitrogen in Liquid Iron and Iron Alloys, Trans. Met. Soc.

AIME, 212, 8691 (1958) (Experimental, Phase Relations, Thermodyn., 19)

[1960Mae] Maekawa, S., Nakagawa, Y., Solubility of Nitrogen in Liquid Iron and Iron Alloys. II. Effect of Nickel,

Cobalt, Molybdenum, Chromium and Vanadium on the Solubility in Liquid Iron (in Japanese), Tetsu

to Hagane, 46(9), 972976 (1960) (Experimental, Phase Relations, Thermodyn., 8)

[1960Peh] Pehlke, R.D., Elliott, J.F., Solubility of Nitrogen in Liquid Iron Alloys. I. Thermodynamics, Trans.

Metall. Soc. AIME, 218, 10881101 (1960) (Experimental, Phase Relations, Thermodyn., 32)

[1961Rao] Rao, M.M., Parlee, N., The Solubility of N in Liquid Fe-V and Fe-Ti Alloys and the Equilibrium in

Reaction xTi + N = TixN (in French),Mem. Sci. Rev. Met., 58(1), 5260 (1961) (Experimental, PhaseRelations, Thermodyn., 6)

[1962Kor1] Korolev, L.G., Morozov, A.N., Solubility of N in Liquid Fe-V Alloys (in Russian), Izv. Vyss. Uchebn.

Zaved., Chern. Metall., 5(7), 2730 (1962) (Experimental, Phase Relations, 5)

[1962Kor2] Korolev, L.G., Morozov, A.N., Equilibrium of N with V in Fe (in Russian), Izv. Vyss. Uchebn. Zaved.,Chern. Metall., 5(9), 3942 (1962) (Experimental, Phase Relations, Thermodyn., 4)

[1963ElT] El Tayeb, N.M., Parlee, N.A.D., The Solubility of Nitrogen and the Precipitation of Vanadium Nitride

in Liquid Iron-Vanadium Alloys, Trans. Met. Soc. AIME, 227, 929934 (1963) (Experimental, Phase

Relations, Thermodyn., 11)

[1963Kor] Korolev, L.G., Morozov, A.N., Formation of V Nitride in Liquid Fe (in Russian), Izv. Vyss. Uchebn.

Zaved., Chern. Metall., 6(4), 4549 (1963) (Experimental, Phase Relations, Thermodyn, 3)

[1965Eva] Evans, D.B., Pehlke, R.D., Equilibria of Nitrogen with Refractory Metals Titanium, Zirconium,

Columbium, Vanadium, and Tantalum in Liquid Iron, Trans. Met. Soc. AIME, 233, 16201624 (1965)

(Experimental, Phase Relations, Thermodyn., 14)

[1966Koe] Kster, W., Horn, W., Damping Investigation on Nitrided Iron-Molybdenum and Iron-VanadiumAlloys (in German), Arch. Eisenhuettenwes., 37, 245252 (1966) (Experimental, Morphology, Mechan.

Prop., Transport Phenomena, 22)

[1966Sch] Schenck, H., Steinmetz, E., Activity, Standart Condition and Coeffitient of Activity (in German),

Stahleisen-Sonderberichte, Dusseldorf: Verlag Stahleisen, (7), 136 (1966) (Thermodyn., Review, 161)

[1967Sch] Schrmann, E., Kunze, H.D., Equivalent Interaction Parameters fort he N and S Solubilities, Activitiesand Activity Coefficients in Three- and Multicomponent Alloys at 1600C (in German), Giesserei-

forschung, 19, 101108 (1967) (Theory, Calculation, Thermodyn., 10)

[1968Uda] Uda, M., Wada, T., Solubility of Nitrogen in Arc-Melted and Levitation-Melted Iron and Iron Alloys,

Trans. Nat. Res. Inst. Met. (Jpn.), 10(2), 7991 (1968) (Experimental, Phase Relations, Thermodyn., 40)

[1969Wad] Wada, H., Solubility of Nitrogen in Molten Fe-VAlloy, Trans. Iron Steel Inst. Jpn., 9, 399403 (1969),

translated from J. Jpn Inst. Met., 33, 720 (1969) (Experimental, Morphology, Phase Relations, Thermo-

dyn., 8)

[1973Bel] Belotskiy, A.V., Marchevskaya, E.I., Permyakov, V.G., Nitride-Phase Formation in Fe-V-N System,

Russ. Metall., (3), 103105 (1973) (Experimental, Phase Relations, Transport Phenomena, 8)

[1973Gul] Gulyaev, A.P., Anashenko, V.N., Karchevskaya, N.I., Larina, O.D., Matrosov, Yu.I., Solubility of

Vanadium and Niobium Nitrides in Iron, Met. Sci. Heat Treat., 15(8), 643645 (1973), translated from

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mental, Morphology, Kinetics, Surface Phenomena, 14)

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[1977Kra] Krawitz, A., X-Ray Studies of Fe-Mo and Fe-V Alloys Nitrided by Constant Activity Aging, Scr.

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Phase Relations, 14)

[1981Ers] Ershov, G.S., Kasatkin, A.A., Influence of Alloying Elements on the Diffusion of Nitrogen in Liquid

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[1981Wad] Wada, H., Pehlke, R.D., Nitrogen Solubility in Liquid Fe-V and Fe-Cr-Ni-V Alloys, Metall. Trans. B,

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[1987Mor] Morita, Z., Tanaka, T., Yanai, T., Equilibria of Nitride Forming Reactions in Liquid Iron Alloys,

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[1987Rag1] Raghavan, V., The Fe-N-V (Iron-Nitrogen-Vanadium) System in Phase Diagrams of Ternary Iron

Alloys, Ind. Inst. Techn., Delhi, 1, 211216 (1987) (Crys. Structure, Phase Diagram, Phase Relations,

Review, 32)

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Techn., Delhi, 1, 143144 (1987) (Crys. Structure, Experimental, Phase Diagram, Phase Relations, 7)

[1987Wri] Wriedt, H.A., Gokcen, N.A., Nafziger, R.H., The Fe-N (Iron-Nitrogen) System, Bull. Alloy Phase

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[1991Fri] Frisk, K., A Thermodynamic Evaluation of the Fe-Ni-N System, Z. Metallkd., 82, 5966 (1991) (Phase

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(1991) (Calculation, Experimental, Phase Diagram, Phase Relations, Thermodyn., 24)

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(1993) (Crys. Structure, Experimental, Transport Phenomena, 12)

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into Molten Iron, Met. Mat. Trans. B, 26B(5), 991995 (1995) (Experimental, Kinetics, Surface

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16 3 FeNV


[1999Lei] Leineweber, A., Jacobs, H., Huning, F., Lueken, H., Schilder, H., Kockelmann, W., -Fe3N:Magnetic Structure, Magnetization and Temperature Dependent Disorder of Nitrogen, J. Alloys

Compd., 288(1-2), 7987 (1999) (Experimental, Crys. Structure, 40)

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Alloyed Iron, Thin Solid Films, 377, 543549 (2003) (Calculation, Interface Phenomena, Phase Rela-

tions, 27)

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Levitation Technique, Arch. Metall., 46(2), 197206 (2001) (Experimental, Phase Relations, Thermo-

dyn., 12)

[2001Lei] Leineweber, A., Jacobs, H., Hunning, F., Luecken, H., Kockelmann, W., Nitrogen Ordering and

Ferromagnetic Properties of -Fe3N1+x (0.10 < x < 0.39) and -Fe3(N0.80C0.20)1.38, J. Alloys Compd., 316,2138 (2001) (Experimental, Crys. Structure, 47)

[2003Gou] Goune, M., Belmonte, T., Redjaimia, A., Weisbecker, P., Fiorani, J.M., Mochel, H., Thermodynamic

and Structure Studies on Nitrided Fe-1.62%Mn and Fe-0.56%VAlloys, Mater. Sci. Eng. A, 351, 2330

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[2003Siw] Siwka, J., Kaputkina, L.M., Shaidurova, E.S., Hutny, A., The Crystallization, Structure and Work

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FeNV 3 17


DOI: 10.1007/978-3-540-70890-2_3

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Iron Sodium OxygenIron Systems: Phase Diagrams, Crystallographic and Thermodynamic Data

Kostyantyn Korniyenko, Hans Leo Lukas

Introduction

Knowledge of the phase equilibria in the iron-sodium-oxygen system and free energies of

formation of sodium ferrites at elevated temperatures is necessary, in the first instance, with a

view to analyze the corrosion behavior of sodium in nuclear reactors and to address the problem

of scabbing and scaffolding in blast furnaces that is due to high alkali content. Information about

phase relations in the Fe-Na-O system is presented in literature by the Fe3O4-NaFeO2 quasibin-

ary section [1984Dai2], liquidus surface of the partial FeO-Fe2O3-NaFeO2 system [1984Dai2],

isothermal sections and phase relations at different temperatures and composition ranges

[1975Cla, 1976Bal2, 1977Kni, 1981Lin, 1984Dai2, 1986Igu, 1993Sri, 1999Kal, 2003Hua2,

2003Lyk] and temperature-composition sections [1940Kni, 1960The, 1962The, 1984Dai1,

1984Dai2]. Crystal structure data obtained by powder- or single crystal X-ray diffraction are

published by [1959Col, 1960The, 1962Roo, 1962The, 1963Sch, 1967Rom, 1970Gro, 1971Tsc,

1974Bar, 1974Rie, 1975Cla, 1975Kol, 1976Bal1, 1976Bal2, 1977Bra, 1977Kni, 1978Bra1,

1978Bra2, 1978Bra3, 1980Kes, 1981Kes, 1981Oka, 1985Fru, 1986Igu, 1997Ded, 2002Ama,

2003Sob1, 2003Sob2]. Thermodynamic aspects of the Fe-Na-O system are reflected in

[1970Gro, 1977Kni, 1977Sha, 1981Lin, 1984Ban, 1984Dai1, 1984Dai2, 1985Ban1, 1985Ban2,

1987Yam, 1988Bha, 1996Zha, 1999Kal, 2003Hua1, 2003Hua2, 2003Lyk]. The applied experi-

mental techniques as well as the studied temperature and composition ranges are listed in

Table 1. Reviews of literature data present information concerning phase equilibria and crystal

structures [1989Rag], thermodynamics [1981Lin, 1999Kal] as well as systematics of crystal

structures of the Fe-Na-O phases [1978Zve, 1982Bau, 1998Wu, 2000Mat, 2003Mue].

In future further studies are desirable on the liquidus and solidus surfaces in the area FeO-

Na2O-NaO3-Fe2O3 as well as on invariant equilibria. More details of isothermal sections at

different temperatures would be useful. New informations may help to find new practical

applications of sodium ferrites.

Binary Systems

The Fe-Na, Fe-O and Na-O binary systems are accepted as compiled in [Mas2]. The assess-

ment of the Na-O system is published with more details by [1987Wri].

Solid Phases

Crystallographic data of all known unary, binary and ternary solid phases are compiled in

Table 2. Compositions of the all reported ternary phases, except the 9 and 12 phases, lie alongthe Na2O-FeO or Na2O-Fe2O3 sections. The composition of the 6 phase, established by[1959Col, 1962The, 1999Kal] as Na10Fe16O29, was later refined by [1962Roo, 1967Rom,

FeNaO 4 1


DOI: 10.1007/978-3-540-70890-2_4

Springer 2009MSIT1

1987Yam, 1996Zha, 1999Kal] to be Na3Fe5O9. For the 2 phase the standard Gibbs energy offormation was determined by [1984Dai1] using emf, but no crystal structure data are known.

For many of the ternary phases the temperature range of stability is not known, except the

temperature of preparation. The crystal structures of the phases 11, 12 and 13 also areunknown and need further experimental clarification.

Quasibinary Systems

The section Fe2O3-Na2O is quasibinary, at least in solid state at lower temperatures. In the

range Fe2O3-NaFeO2 [1940Kni, 1984Dai1] assume a simple eutectic near 1150C and Na/(Na

+Fe) = 0.36, whereas [1960The, 1962The] found in solid state the 6 phase, stable between1100 and 755C. Additionally they found a metastable solid solution of Na2O in Fe2O3,decomposing on heating above 650C. The pure Fe2O3 before melting decomposes into Fe3O4and O2 gas. Thus the two-phase field L + Fe2O3 must end before it reaches the Fe2O3 side of the

section. The liquidus temperature of NaFeO2 is assumed as 1330C [1940Kni, 1984Dai1].

Between NaFeO2 (1-1) and Na2O there are at least five more phases in this quasibinarysection, well established by the determination of their crystal structures: Na4Fe2O5 (4),Na14Fe6O16 (8), Na3FeO3 (10), Na8Fe2O7 (5) and Na5FeO4 (7). On the temperature rangesof stability and on equilibria with melt no experimental data are published for these phases. A

further phase, 13, between 6 and 1, postulated by [1981Lin], was denied by [1962The,1999Kal]. In Fig. 1 the Fe rich part of this section is constructed. The equilibria between gas,

liquid, Fe2O3 and Fe3O4 must be taken as tentative only. The Fe rich liquid, due to Fe+2 ions

does not reach the section and Na rich liquid may dissolve more O than corresponding to the

section, due to peroxide or ozonide ions known in the binary Na-O liquid. On the transition

between both cases data are lacking.

The section FeO-Na2O is quasibinary in the range Na2FeO2-Na2O [1984Dai1, 1984Dai2].

Between Na2FeO2 and FeO it is clearly a not quasibinary isopleth, Fig. 2. At lower tempera-

tures also the range Na2O to Na4FeO3 looses the quasibinary character. [2003Hua2] calculated

an invariant reaction: Na(liq) + Na4FeO3 Na2O + (Fe) at 421C. This temperature may bea reasonable estimate. [1993Sri] found this reaction experimentally and located it somewhere

between 353 and 487C.

The Fe3O4-NaFeO2 section is approximately quasibinary. The Fe3O4 phase has some

homogeneity range towards a composition NaFe5O8, corresponding to the spinel structure

of Fe3O4, in which the divalent Fe+2 ions may be replaced by 0.5(Fe+3 + Na+1). Due to the

difference between this direction and the section plane the tie lines of the two-phase fields

containing Fe3O4 are slightly outside the section plane. Contrary to a strictly quasibinarysection all these fields contain a trace of FeO and thus are three-phase fields. Figure 3 shows

this approximately quasibinary section as published by [1984Dai2] with correction of a typing

error. The horizontal lines at ca. 1150 and 980C correspond to the invariant four-phase

equilibria L Fe3O4 + FeO + 1 and 1 1, Fe3O4, FeO, respectively.

Invariant Equilibria

[1984Dai2] constructed the liquidus surface of the FeO-Fe2O3-NaFeO2 partial system. These

authors mention four invariant four-phase reactions. In Fig. 4 the corresponding reaction

2 4 FeNaO


scheme is tentatively constructed. It covers the area Fe-Na2FeO2-NaFeO2-Fe2O3. The 6 phaseis tentatively included, assuming no participation in an invariant equilibrium. The three-phase

equilibria of the quasibinary part Na2O-Na2FeO2 can be approximated as degenerate four-

phase equilibria with Fe in equilibrium. By this consideration the congruent melting point of

Na2FeO2 in the quasibinary part of the Na2O-FeO section is also a degenerate maximum of the

three-phase equilibrium L + Fe + Na2FeO2. Thus only the formation of the three-phase

equilibrium L + 1 + 2 remains unsolved in the reaction scheme. The compositions of liquidin the invariant equilibria are too unprecise to justify a tabulation. In Fig. 4 the polymorphic

transformations of (Fe) and NaFeO2 (1) are neglected. As at both compositions all phases arenearly stoichiometric, all these transformations are degenerate with the equations (Fe) (Fe), (Fe) (Fe), 1 1 or 1 1. All other phases participating remain inequilibrium at higher and lower temperatures without taking part at the reactions. Phase 12was not mentioned by [1984Dai2] and is not implemented in Fig. 4.

Outside the range of Fig. 4 the existence of the invariant four-phase equilibrium

L(Na) + Na4FeO3 (Fe) +Na2O is well established, its temperature is inside the interval487-353C [1993Sri], but could not be located more precisely.

Liquidus, Solidus and Solvus Surfaces

The liquidus surface projection of the partial FeO-Fe2O3-NaFeO2 system is shown in Fig. 5,

based on [1984Dai2]. Isotherms at the temperatures of 1300, 1400 and 1500C are plotted. No

data concerning solidus or solvus surfaces were found in literature.

Isothermal Sections

The isothermal section of the partial Fe-Fe2O3-NaFeO2 system at 1000C is shown in Fig. 6, as

constructed by [1986Igu], based on experimental studies of the FeO-Na2O solid solution in

equilibrium with Ar-H2-H2O mixtures. The shapes of the single phase fields of the FeO-Na2O

and Fe3O4-Na2O solid solutions agree well with the findings of [1975Cla, 1976Bal2, 2003Lyk],

except, that [1976Bal2, 2003Lyk] postulate the existence of 12, which is not mentioned by[1975Cla, 1984Dai2, 1986Igu]. [1986Igu] also ignored the 6 phase, which is reported to bestable at 1000C [1962The, 1999Kal].

Participation of the 6 phase in equilibria at 1000C was also reported in the works of[1960The] and [1962The, 1999Kal] devoted to constitution of the NaFeO2-Fe2O3 tempera-

ture-composition section. The partial isothermal section at 1000C in the FeO-Fe3O4-

NaFe5O8-NaFeO2 range was also experimentally constructed by [2003Lyk]. These authors

report the 13 phase, but do not show the 6 phase. In general, their data conform to the data of[1986Igu] satisfactorily. In their studies of corrosion of steel by liquid Na [1977Kni] found at

650C the 3 phase in equilibriumwith (Fe) and liquid sodium, while at 400C the tie line Na-3 is replaced by an equilibrium between Na2O and (Fe). In the calculations of [2003Hua2]the corresponding four-phase reaction was located at 421C. [1993Sri] experimentally con-

firmed this four-phase reaction to happen between 353 and 487C. [1981Lin] used the

SOLGAMIX-PV computer program to calculate phase equilibria in the temperature range

from 447 to 607C in the partial Na-Na2O-Fe2O3-Fe system. They reported the ternary phases

1, 2, 3, 5, 6, 7, 10 and 13 to take part in equilibria in this temperature interval. However,

FeNaO 4 3


DOI: 10.1007/978-3-540-70890-2_4

Springer 2009MSIT1

they do not mention the eutectoid decomposition of FeO at 570C, due to which FeO should

not take part in equilibria far below 570C. The 595C isothermal section, constructed by

[1984Dai2] from their experimental data (Fig. 7), differs as far as the three iron oxides FeO,

Fe3O4 and Fe2O3 all are in equilibrium with NaFeO2 (1), whereas [1981Lin] show them inequilibrium with Na3Fe5O9 (6) or Na4Fe6O11 (13). [1984Dai2] left the phases 4, 8, 10, 5and 7 outside their investigated range. [2003Hua2] published six calculated isothermalsections between 25 and 727C. In this calculation they did not include the phases 2, 4, 6,8, 9, 11, 12 and 13. The thermodynamic dataset used for the calculation is published. Apartfrom the excluded phases these sections agree well with Fig. 7. The phase 5 appears to bestable only above 364C and the invariant reaction L(Na) + Na4FeO3 Fe +Na2O is located at421C. Some of the dashed lines in the O rich part of Fig. 7 may be replaced by equilibria with

Na- and O rich liquid.


Besides the partially or approximately quasibinary sections shown in Figs. 1 to 3 the tempera-

ture-composition section NaFeO2-FeO is shown in Fig. 8 based on data of [1984Dai1,

1984Dai2]. The authors qualify this section as qualitative representation of the phases in

this section.

Thermodynamics

Information about thermodynamic properties of the Fe-Na-O alloys is widely represented in

the literature. Data concerned the reactions are listed in Table 3. The chemical equilibria of

gas-slag reactions have been studied by [1984Ban, 1985Ban1, 1985Ban2] to clarify the effect of

soda on the thermodynamic properties of slags in the hot metal treatment. The FeO-Na2O

slags were studied at 1610C being equilibrated with pCO2 = 1.013 bar by using a platinum

crucible. The influence of slag composition on the activity of iron oxide and the Fe3+/Fe2+

ratios has been determined. It has been clarified, that the results can be expressed in terms of

the Lumsdens regular solution model over a wide range of compositions. [1984Dai1], besides

the results presented in T

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