Microstructure, martensitic transformation and properties in the Ni50Mn30Ga16Cu4 ferromagnetic shape memory alloy

A Heusler Ni50Mn30Ga1Cu4 alloy with the highest compressive strength has been obtained by substituting 4 at% Cu for Ga in a ternary Ni50Mn30Ga20 ferromagnetic shape memory alloy. It is shown that the highest compressive strength of 3178.9 MPa with a fracture strain up to 13.6% can be achieved at room temperature. To date, this is the highest compressive strength reported in the Ni–Mn–Ga alloy system. The martensitic structure changes from 7M with 0 at% Cu to non-modulated T martensite with 4 at% Cu . In addition, the Cu doping markedly increases the martensitic transformation temperature from 82.1 °C to 136.6 °C. At the same time, the Curie temperature and saturation magnetization for the Ni50Mn30Ga16Cu4 alloy slowly decrease due to the 4 at% Cu addition.