Pinning-induced stabilization of martensite: Part I. Stabilization due to static pinning of interfaces

Abstract

A simple model, based on thermoelastic force balance, is suggested for the part of the stabilization of martensite resulting from pinning of interfaces, which is complementary to atomic reordering. A simple static solution is obtained for the overheating required to initiate the motion of an interface, pinned by quenched-in defects. Qualitative analysis of the pinning-induced stabilization in polyvariant sample is performed, assuming fractal fragmentation of variant structure. The model predicts that: • shift to higher temperatures and broadening of the reverse transformation range occurs during pinning-induced stabilization; • if the reverse transformation remains complete, pinning-induced stabilization does not break the thermoelastic sequence of the transformation; • kinetics of shift and broadening of the reverse transformation can be different; the shift of the reverse transformation start temperature first reaches saturation value, whereas the increase of the transformation finish temperature is a more long-term process. Numerical estimates show that pinning can easily account for the experimentally observed values of the thermal stabilization of martensite.