Martensitic transformation and phase stability of In-doped Ni-Mn-Sn shape memory alloys from first-principles calculations

The effect of the alloying element Indium (In) on the martensitic transition, magnetic properties, and phase stabilities of Ni8Mn6Sn2-xInx shape memory alloys has been investigated using the first-principles pseudopotential plane-wave method based on density functional theory. The energy difference between the austenitic and martensitic phases was found to increase with increasing In content, which implies an enhancement of the martensitic phase transition temperature (T-M). Moreover, the formation energy results indicate that In-doping increases the relative stability of Ni8Mn6Sn2-xInx both in austenite and martensite. This results from a reduction in density of states near the Fermi level regions caused by Ni-3d-In-5p hybridization when Sn is replaced by In. The equilibrium equation of state results show that the alloys Ni8Mn6Sn2-xInx exhibit an energetically degenerated effect for an In content of x = similar to 1.5. This implies the coexistence of antiparallel and parallel configurations in the austenite. (C) 2014 AIP Publishing LLC.