Morphology and heat treatment of a Fe60Cr30Co10 magnetic alloy

Ordering and phase separation in alloys of the Fe–Co system

“…Changes of properties to which this phase transformation can bring about have been clarified in study of the Fe 60 Cr 30 Co 10 alloy [12]. The alloy has been heat treated in such a way as to achieve a maximum level of the coercive force.…”

“…The alloy has been heat treated in such a way as to achieve a maximum level of the coercive force. That heat treatment is bound to include the follow stages [12]: waterquenching initially from 1200-1300 • C and then from 700 • C for about 0.5 h with the aim to obtain 100% ␣-solid solution; 550 • C aging during a time it takes for a hardness peak achievement with the aim to form the ␣ 1 + ␣ 2 microstructure; slow cooling from 550 to 500 • C with the aim to achieve maximum coercive force. Fig.…”

“…8) and the Co-enriched ␣ 1 phase (in the form of the dark blurred boundaries between ␣ 2 micrograins) is formed. Inside these two types of precipitates the chemical interactions between Fe and Co atoms and between the Fe and Cr ones have different signs at 550 • C: between Fe and Co atoms the sign of the chemical interaction is negative (tendency towards ordering), and between Fe and Cr atoms the sign is positive (tendency towards phase separation) [12]. So, the boundaries between ␣ 1 and ␣ 2 phases are not only the ones between phases with the different chemical composition, but also the ones, in going through which a sign of chemical interaction between species is changed [12].…”