J. Phys. IV France 11 (2001) Pr8-205-Pr8-210
Effect of ausaging on the morphology of martensite in an Fe-25%Ni-7.5%Si alloyY. Himuro, O. Ikeda, R. Kainuma and K. Ishida
Department of Materials Science, Graduate School of Engineering, Tohoku University, Aramaki Aoba-yama 02, Sendai 980-8579, Japan
The martensitic transformations in an Fe-25%Ni-7.5%Si (mass%) alloy ausaged under various conditions were investigated by means of optical and transmission electron microscopy, differential scanning calorimetry, electrical resistivity-temperature measurements and hardness-testing. It was clarified that nanoscale particles of γ'-(Ni,Fe)3 with Ll2 structure were formed in the austenite matrix by ausaging between 400 and 600°C, while no precipitation occurred due to ausaging at 700°C. The Ms temperature was depressed by ausaging at 400 and 500°C, but hardly changed when the ausaging temperature was 600°C. It was observed that the morphology of martensite which was lenticular in unaged specimen changed to a mixture of lenticular and thin plate by ausaging at below 600°C.
© EDP Sciences 2001