Structural and magnetic properties of Cr-doped Ni–Mn–In metamagnetic shape memory alloys

Abstract

The effect of the partial substitution of Mn by Cr on the structural and magnetic properties of Ni–Mn–In metamagnetic shape memory alloys is investigated. It is found that a Cr-rich second phase appears for quite low Cr concentrations, pointing out a very low solubility of Cr in Ni–Mn–In. Nevertheless, the martensitic transformation (MT) temperature of the doped alloys can be related to the variation in the electron concentration in the matrix phase, just as it occurs in the ternary Ni–Mn–In system. The effect of magnetic field on the structural transformation has been evaluated on both a ternary and a quaternary alloy. It is shown that the presence of the second phase reduces the magnetically induced shift of the MT and the associated magnetocaloric effect, thus limiting the potential applicability of Ni–Mn–In alloys. The obtained results prevent the addition of high amounts of Cr to Ni–Mn–In.