Hysteretic behavior in an Fe-based shape memory alloy under tensile/compressive cyclic thermomechanical loading

The thermomechanical hysteretic behavior in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy is experimentally investigated under tensile and compressive cyclic thermomechanical loading. Similar to the other shape memory alloys, such as Ti-Ni and Cu-based alloys, the Fe-based shape memory alloy also exhibits the cyclic effect which appears macroscopically as the change in the hysteresis loop with cycling. The convergence to a limit loop is, however, not observed in the present alloy. The cyclic effect on the residual strain, the transformation strain and the martensite start stress is explained by the two metallurgical processes; the accumulation of the perfect dislocations and the shape irreversibility in the reverse transformation.