On the explanation for the time-dependence of B2 to R martensitic transformation in Ti50Ni47Fe3 shape memory alloy

Abstract

Much debate has arisen because some experimental results indicated the occurrence of isothermal character in typical athermal martensitic transformation. The aim of this present work is to clarify this point. The nature (isothermal or athermal) of thermoelastic transformation in a Ti50Ni47Fe3 shape memory alloy was examined using classical thermal analysis method. Although a time-dependent phenomenon of B2-R martensitic transformation during cooling was observed. It was interpreted well from the viewpoint of the shift of martensitic transformation temperatures under different temperature rates, which is a process associated with time and we conclude that this is the origin of “isothermal” character, and the transformation itself is athermal instead of isothermal.