Giant 5.8% magnetic-field-induced strain in additive manufactured Ni-Mn-Ga magnetic shape memory alloy

Abstract

Laser powder bed fusion (L-PBF) additive manufacturing process was employed to manufacture polycrystalline Ni-Mn-Ga samples. The samples were heat-treated for chemical homogenization and grain growth. It is demonstrated that the chemical composition, resulting martensitic crystal structures, and phase transformation temperatures of the L-PBF-built Ni-Mn-Ga can be precisely changed in-situ by controlling the selective evaporation of Mn through adjusting the process parameters. Subsequently, repeatable and fully reversible magnetic-field-induced strain of 5.8% was measured in a single crystalline grain of an additive manufactured polycrystalline Ni-Mn-Ga sample exhibiting a 10M martensitic structure at ambient temperature. The results indicate that L-PBF can be used to manufacture Ni-Mn-Ga devices containing active parts that can be strained by an external magnetic field.