Giant magnetic-field-induced strains in polycrystalline Ni–Mn–Ga foams

The magnetic-field-induced strain in magnetic shape-memory alloys can be used in several types of application. However, the strain is high (10%) only in single-crystalline specimens, which are difficult and expensive to obtain. Polycrystalline samples with comparable strain have now been fabricated by introducing pores of similar size to the grains.