Effect of alloying element Al substitution on Ni-Mn-Sn shape memory alloy by first-principle calculations

The effect of alloying element aluminum on the magnetic properties and martensitic transition in Ni8Mn6Sn2-xAlx shape memory alloys has been studied using the density-functional theory. It is found that the tetragonality, c/a, of the martensite phase increases gradually from 1.30 to 1.34 with increasing Al content. The equilibrium equation of state results show that the alloys Ni8Mn6Sn2-xAlx exhibit an antiferromagnetic-ferromagnetic phase transition in the austenite phase with x increasing. In particular, when x = 2, an unique magnetic transition occurs from ferromagnetic austenite (6.30 mu B/f.u) to antiferromagnetic martensite (1.82 mu(B)/f.u), as characterized by the spin polarized electronic density of states. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772618]