Martensitic and magnetic phase transitions in ternary ferromagnetic alloys Ni–Mn–Ga

Abstract

Analysis of experimental data on martensitic T m and magnetic T C phase transition temperatures of ternary ferromagnetic shape memory alloy system Ni–Mn–Ga points to the existence of three distinctive regions in which (i) martensitic transformation occurs when in ferromagnetic state ( T m < T C ) , (ii) martensitic and magnetic transitions are coupled ( T m = T C ) , and (iii) martensitic transformation takes place well above ferromagnetic ordering temperature, T m > T C . The coupling of martensitic and magnetic phase transitions is observed in the alloys with average electron concentration e / a ≈ 7.65 .