Training of the Ni-Mn-Fe-Ga ferromagnetic shape-memory alloys by cycling in a high magnetic field

The temperature and magnetic field dependencies of Ni-Mn-Ga polycrystals deformation are investigated. Ingots were prepared by arc-melting in argon atmosphere and further annealing. A training procedure (cycling across the martensitic transition point) for the two-way shape-memory effect was performed with Ni$_{2.16}$Fe$_{0.04}$Mn$_{0.80}$Ga samples. Changes in sample deformations were noticed with changing the magnetic field at a constant temperature. The first cycle deformation increment as compared with the initial value (in the austenitic state at zero field) in the course of the martensitic transition was 0.29%, and 0.41% and 0.48% for the second and third cycles, respectively.Comment: Presented at the Second Moscow International Symposium on Magnetism (Moscow-2002

An efficient control of Curie temperature TCT_C in Ni-Mn-Ga alloys

We have studied the influence of alloying with a fourth element on the temperature of ferromagnetic ordering $T_C$ in Ni-Mn-Ga Heusler alloys. It is found that $T_C$ increases or decreases, depending on the substitution. The increase of $T_C$ is observed when Ni is substituted by either Fe or Co. On the contrary, the substitution of Mn for V or Ga for In strongly reduces $T_C$.Comment: presented at ICM-200