The magnetic and microstructural evolution of Ni45Mn24Ga23Co4Cu4 Heusler alloy ribbons

Ni45Mn24Ga23Co4Cu4 Heusler alloy ribbons were prepared using the melt-spinning technique. The ribbons contain a mixed phase of austenite and martensite. The experimental results indicate that a synchronized change in the martensitic transformation and grain growth occur with increasing annealing temperatures. Moreover, the magnetic domain sizes at the wheel surface of the ribbons increased when the ribbons were annealed at temperatures >573 K, and the grain sizes did not change until the ribbons were annealed at 1173 K, which led to the false appearance of inconsistent magnetostructural and microstructural evolution occurred at the wheel surface. This finding might result from the hysteresis of grain growth behavior at the wheel surface compared with that inside the ribbons. Furthermore, the bending experiment results indicate that the Ni45Mn24Ga23Co4Cu4 alloy ribbons exhibit good ductility, which means that melt-spun NiMnGa alloy ribbons can exhibit good ductility when doped with Co and Cu. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim