Stress-induced martensite in single crystals of an Fe-23Ni-5Cr alloy

Abstract

Asymmetrical uniaxial stress was applied to single crystals of an Fe-23%Ni-5%Cr alloy to induce martensitic transformations. Slip and martensitic transformations occurred concurrently during the deformation and the normal temperature dependence of yield stress was observed. Stress-induced martensite in this alloy was needle-like surface martensite. Determination of martensite varients was performed using an X-ray Weissenberg technique. Distribution of variants was very sensitive to the sense of the applied stress and the results were well explained by postulating the {111} f 〈211〉 f shear systems in the initial stage of the transformation. Phenomenological calculation showed less rational correlation to the observed stress-induced variants. The stronger tendency towards martensite formation in tension as compared to compression was also explained using the above postulate.