Martensitic transformations in the powders of Ni-Mn-Ga alloys fabricated by a method of spark erosion

The structure and magnetic properties of Ni-Mn-Ga alloy powders fabricated by the volume electroerosion method are investigated. The particles of a powder have a spherical form with an average size of similar to 2.7 mu m. As shown by x-ray analysis, the particles are in a martensitic state at the room temperature. The magnetization of powder particles is substantially increased during the process of annealing that specifies on the increase of the atomic long-range order degree (of L2(1) type) in a solid solution based on the Ni2MnGa compound. The used method of the electroerosion dispersion provides the high-rate cooling of particles that, probably, allows preventing an atomic long-range ordering in most powder particles.