Thermal and stress-induced martensitic transformations in quaternary Ni50Mn37(In, Sb)13 ferromagnetic shape memory alloys

This study investigated the martensitic transformation and the mechanical behaviour of quaternary Ni50Mn37In13−xSbx (x = 0, 2, 6, 8, 10) Heusler alloys. Substitution of Sb for In was found to reduce the orthorhombic distortion of the martensite form the L21 austenite, but increased the transformation volume change. The critical temperatures of the transformation are found to decrease nearly linearly with increasing valence electron concentration caused by Sb substitution for In, with a linearity coefficient of ∼15 K per at% of Sb. The transformation latent heat and the transformation entropy change decreased with increasing Sb content, with two different composition dependencies in concentration ranges of 0 < x < 6 and x > 6. This is attributed to different magnetic states of the martensite. A recoverable transformation strain of 0.46% was obtained in the polycrystalline Ni50Mn37In3Sb10 alloy. An effect of stress-induced martensite stabilization was observed in the Ni50Mn37In7Sb6 sample.