Fe-Ni-Al phase diagram in ALNI type permanent magnets related area

Abstract

With 36 alloys selected from indications provided first by differential thermal analysis and by other methods of analysis and physical measurements, it has been possible to specify accurately the Fe-Ni-Al ternary diagram. This research enabled us to : 1. Give a better definition of the solid/liquid state limits, α and γ phases existence fields, miscibility-gap extent, Curie temperature variations in relation with the alloy composition, 2. Prove that for some ternary alloys, there does appear a miscibility gap related to the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\alpha\rightarrow\alpha_{1}+\alpha_{2}</tex> reaction. The three phases having very close lattice parameter are b.c.c., α <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> phase being an ordered phase (superstructure). 3. Show that, for an alloy in the miscibility gap, the α <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> and α <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> phase compositions at room temperature are not constant.