Phase transformation and mechanical properties of (Ni56.5Fe17Ga26.5)100−xGex ferromagnetic shape memory alloys

The effect of Ge addition on the microstructure, transformation temperatures and mechanical properties of (Ni56.5Fe17Ga26.5)100−xGex ferromagnetic shape memory alloys was investigated. With the increase of Ge content in these alloys the martensitic transformation temperatures decrease almost linearly from higher than 100 °C down to −70 °C or even lower that is attributed to the change of the electron concentrations of the Ni-Fe-Ga(Ge) alloys. The addition of Ge also significantly enhances the compression strength and the ductility of the alloys. The determined relationships between transformation temperatures and the mechanical properties and the Ge content will be useful for designing a suitable Ni-Fe-Ga(Ge) alloy device with a required martensitic transformation temperature and optimized mechanical property.