Athermal nature of the martensitic transformation in Heusler alloy Ni–Mn–Sn

Martensitic transformations are generally classified into two groups, namely athermal and isothermal, according to their kinetics. In case of athermal transformations, the amount of the product phase only depends on temperature, and not on time. However, much debate rises about this issue due to unexpected experimental observations of isothermal effects in typically athermal transformations. Considering that the wide applications of Heusler Ni–Mn based materials are based on martensitic transformations, it is of importance to clarify the nature of their martensitic transformation. In this paper, we made an effort to study isothermal effects in a Ni–Mn–Sn alloy using differential scanning calorimetry (DSC). It is proposed that the martensitic transformation of Ni–Mn based materials is athermal in nature although a time-depending effect is observed through DSC interrupted measurements.

► A time-depending effect is observed through DSC interrupted measurements.
► The time effect is originated from the Ms migration under different thermal rates.
► The martensitic transformation of Ni–Mn based materials is athermal in nature.