Martensitic transformation of (Ni55.3Fe17.6Ga27.1)100−xCox magnetic shape memory alloys

The effects of Co on the martensitic transformation and magnetic properties of Ni–Fe–Ga magnetic shape memory alloys were investigated. An unusual phenomenon of one martensitic transformation and two intermartensitic transformations in the differential scanning calorimetry curve for Ni55.3Fe17.6Ga27.1 alloy was observed. With 3 at.% Co addition in Ni55.3Fe17.6Ga27.1 alloy, the Ms temperature increased from 313.44 to 405.07 K, the saturation magnetization was improved from 21.64 to 97.67 emu/g and the magnetocrystalline anisotropy constant was enhanced from 1.253 × 106 to 4.035 × 106 erg/cm3. In addition, the magnetic susceptibility also increased obviously in the low magnetic field. It is suggested that alloying with Co is an effective way to develop low-field, high-temperature and high-performance Ni–Fe–Ga magnetic shape memory alloys.