A 1% magnetostrain in polycrystalline 5M Ni–Mn–Ga

Magnetostrain is achieved by twin boundary motion in magnetic shape memory materials. A 1% strain could be achieved in textured polycrystals of Ni–Mn–Ga at room temperature. Ni50Mn29Ga21 was directionally solidified in order to obtain a texture parallel to the heat flow. The alloy was heat treated for chemical homogenization and stress relaxation in the austenite state. Thermomechanical training was employed to decrease the twinning stress and to enhance the strain by simplification of the variant microstructure. Investigations at slightly elevated temperatures were performed to increase the magnetostrain to 1%.