Microstructure and mechanical properties in Ni 45·4 Mn 39·5 In 13·1 Gd 2 alloy with high transformation temperature

A Heusler Ni_45·4Mn_39·5In_13·1Gd₂ alloy with high transformation temperature has been obtained by substituting 2 at-Gd for Mn in a ternary Ni_45·4Mn_41·5In_13·1 ferromagnetic shape memory alloy. It is shown that the microstructure of Ni_45·4Mn_39·5In_13·1Gd₂ alloy consists of a matrix and a Gd rich phase. The Ni_45·4Mn_39·5In_13·1Gd₂ alloy exhibits a martensitic transformation start temperature of 726 K, and the transformation hysteresis is A_f−M_s = 148°C. At room temperature, non-modulated martensite of tetragonal L1₀ structure is observed in Ni_45·4Mn_39·5In_13·1Gd₂ alloy. In addition, it is revealed that the addition of Gd significantly enhances the compressive strength and improves the ductility of Ni_45·4Mn_39·5In_13·1Gd₂ alloy.