Obtaining of Ni-Mn-Ga magnetic shape memory alloy by annealing electrochemically deposited Ga/Mn/Ni layers

Ni-Mn-Ga thin films are promising candidates for MicroElectroMechanical Systems. Triple-layers of nickel, manganese, and gallium were electrodeposited from chemical solutions on to tungsten and molybdenum refractory metal substrates. These layered films were subsequently annealed at 800 to 900 °C to form a Ni-Mn-Ga Heusler alloy by diffusion. To evaluate the quality of the film, the magnetization of the Ni-Mn-Ga film was measured and normalized by the magnetization of nickel, yielding the relative magnetization. Due to the formation of Ni-Mn-Ga during annealing, the relative magnetization was approximately 2 times larger than the tri-layered as-plated film. These results are comparable to bulk Ni-Mn-Ga reference samples. X-ray diffraction measurements confirmed that the material was present as a mixture of L21-ordered austenite as well as modulated 10 M and non modulated martensite with manganese oxide impurities.

► Ni-Mn-Ga formed by interdiffusion of elemental films formed by electrodeposition.
► Relative magnetization increased upon annealing, indicating desired alloy formation.
► X-ray diffraction revealed austenite and martensite phases, plus oxide impurities.