The suppression and recovery of martensitic transformation in a Ni-Co-Mn-In magnetic shape memory alloy

The intrinsic mechanism of the martensitic transformation (MT) suppression observed in Ni-Co-Mn-In alloys fabricated under non-equilibrium conditions still remains mysterious. Here, we used the undercooling technique to obtain a solidified microstructure in non-equilibrium state, subsequently leading to MT suppression even further cooling to 10 K. It was found that primary dendrite-like In-depleted precipitates occurred during solidification under a large undercooling. After a prolonged annealing, the MT interestingly appeared again due to the dissolution of the precipitates and the recovery of equilibrium chemical composition in the matrix.