Phase equilibria and composition dependence of martensitic transformation in Ni-Mn-Ga ternary system
- 材料学院－已发表论文 
Phase equilibria of Ni-Mn-Ga ternary system at 800 degrees C, 900 degrees C and 1000 degrees C were experimentally investigated by the diffusion couples and equilibrated alloys. The results show that the bcc phase possesses a wide composition range at high temperature. And the liquid and bcc phases extend to the Ni-Mn side and the region of bcc phase becomes longer and narrower with increasing temperature. A new ternary intermetallic compound (Ni, Mn)(2)Ga with the Mn2Ge-type hexagonal structure is present at 800 degrees C, but it disappears at 900 degrees C and 1000 degrees C. Based on the obtained information of phase equilibria, the composition dependence of martensitic transformation on the composition region of Ni2MnGa alloys was discussed. The present study may be useful for structural analysis and phase identification, as well as estimation of martensitic transformation temperatures of Ni-Mn-Ga alloys. (c) 2011 Elsevier Ltd. All rights reserved.