Morphology and crystallography of martensite in Fe-23% Ni-0·38% C alloy induced by plastic deformation of austenite

A tensile deformation at the temperatures between Ms and Md induces in Fe-23% Ni-0·38% C alloy the so-called butterfly martensite, whose morphology is different from that of thermally transformed martensite. The amount of these butterflies increases gradually with deformation and contributes to the transformation — induced plasticity. The difference in morphology corresponds with a different structure, substructure and crystallography and it is caused by the change of transformation mechanism.The author would like to express his thanks to Ing. P.Michalika for his help with metallographic preparation of specimens.