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The effect of austenitizing time on the formation of martensite in Fe–24.5%Ni–4.5%Si alloy has been studied by means of transmission electronmicroscope (TEM), scanning electronmicroscope (SEM) and Mössbauer spectroscopy technique. TEM and SEM observations revealed that the martensite morphology was found to be closely dependent on the austenitizing time. The orientation relationship between austenite and thermally induced martensite was found as the Kurdjumov-Sachs type. The volume fraction changes of martensite and austenite phases, the hyperfine magnetic field of martensite phase and isomery shift values have been determined by Mössbauer spectroscopy. The Mössbauer study also revealed that the martensite volume fractions increased with increasing austenite grain size. [ABSTRACT FROM AUTHOR]

Abstract: The paramagnetic–magnetically ordered transition and the effect of Mo content on the magnetic properties of martensite phase in Fe–30% Ni–x% Mo alloys have been investigated by AC susceptibility and Mössbauer spectroscopy. The results show that martensitic transformation temperature (M S) indicates the magnetic transition from paramagnetic to magnetically ordered state. Hyperfine magnetic field, isomery shift and volume fractions of phases were determined by Mössbauer spectroscopy. It is also found that volume fraction of thermally induced martensite and M S temperature decreased with the increasing Mo content. [Copyright &y& Elsevier]