Microstructure and magnetic properties of Co-doped rapidly solidified Ni ₅₀ Mn _25−x Co _x Ga ₂₅ Heusler alloys

Cobalt-doped melt-spun ribbons of Ni ₅₀ Mn _25−x Co _x Ga ₂₅ were prepared to study the influence of cobalt on the magnetic properties of the NiMnGa based Heusler alloy. Bulk specimens were also prepared for a comparative study. The bulk specimens and the melt spun ribbons were annealed at 900 °C for 5 h followed by quenching. Microstructural studies revealed an extensively twinned structure which is beneficial for magnetic field induced strain. The magnetization measurements showed a reduction in the moment with an increase in the cobalt content from 78.4 emu/g to 52.7 emu/g for Co (x = 6) and Co (x = 10), respectively. A reduction was also observed in the T _C when cobalt content was increased from Co (x = 6) (T _C = 386 K) to Co (x = 10) (T _C = 263 K).