METASTABLE ORDER-DISORDER TRANSITION AND SIGMA PHASE FORMATION IN FE-V BINARY-ALLOYS

The influence of binary and ternary alloying compositions and heating rate on the σ formation reaction are studied. Several ways are developed to supress the stable α phase formation and to understand the metastable CsCl-type order-disorder transition in Fe-V alloys. The Fe-V ordered phase has a metastable critical transition temperature of between 850 and 880° C at equiatomic composition, and the so called 650° C anomaly" corresponds to the 550° C anomaly in Fe-Co alloys. The σ formation reaction does not commence most easily at equiatomic composition but at the iron-rich side of the 40 at. % V alloy. The Influence of ternary alloying additions on the σ formation in Fe-V alloys depends on the relative stabilities of the binary σ phase with iron or vanadium. © 1979 Chapman and Hall Ltd."