Grain size effect on martensitic transformation, mechanical and magnetic properties of Ni–Mn–Ga alloy fabricated by spark plasma sintering

The sintered Ni–Mn–Ga alloys with various grain sizes have been fabricated by using the spark plasma sintering method. The effect of grain size on martensitic transformation, mechanical and magnetic properties of Ni–Mn–Ga alloys have been investigated for the first time. The results show that martensitic transformation and transformation hysteresis are significantly affected by the grain size. All as-sintered Ni–Mn–Ga alloys exhibit high saturation magnetization despite their different grain sizes. Moreover, it is found that the grain size plays important roles on mechanical properties. The sintered specimen with appropriate grain size exhibits the highest fracture strain reported so far.

► Ni–Mn–Ga shape memory alloys with various grain sizes have been fabricated by the spark plasma sintering technique. ► The effect of grain size on martensitic transformation, mechanical and magnetic properties has been studied for the first time. ► Martensitic transformation and transformation hysteresis are significantly affected by the grain size. ► The highest fracture strain of 29% up to now has been reported in the sintered specimen with appropriate grain size.