Phase Transformation in the Process of Ni52.97Mn23.58Ga23.45 Powders Prepared

The changes of phase transformation temperature and structure of Ni_52.97Mn_23.58Ga_23.45 in the progress of the alloy powders preparing have been investigation. The Ni_52.97Mn_23.58Ga_23.45 particles exhibit an intergranular fracture mode in the process of the first hammer crushing. After been balling, the particles turned into flake-shape powders which the mean size was about 20 ´m. With the differential scanning calorimetry testing, phase transformation peak of hammer crushing particles turned to sharper after being annealed, but the phase transformation temperature little changed. When the particles were balling to powders, the phase transformation peak disappeared. After being annealing, the powders phase transformation peak appeared although the phase transformation temperature was lower 7-10K than the annealed particles´. The crystal structures of particles and powder also were the mixtures of the martensitic phase and austenitic phase.