Ni56Mn25-xCuxGa19 (x=0, 1, 2, 4, 8) high-temperature shape-memory alloys
- 材料学院－已发表论文 
Ni56Mn25-xCuxGa19 (x = 0, 1, 2, 4, 8) alloys were investigated as high-temperature shape-memory alloys (SMAs), with regards to their microstructure, martensitic transformation behavior as well as high-temperature shape-memory effect. These alloys exhibit single martensitic phase with tetragonal structure for x < 2, and dual phases containing martensite and gamma phase with fcc structure for x >= 2. The peak temperature A(p) for reverse martensitic transformations increases monotonically from 452.4 degrees C for x = 0 to 529.9 degrees C for x = 2 in Ni56Mn25-xCuxGa19 (x = 0, 1, 2, 4, 8) alloys. But when the Cu content is higher than 2 at.%, A(p) remains almost constant at about 530 degrees C upon formation of the gamma phase. The variations of the martensitic transformation temperatures and shape-memory effects with Cu contents correlate with changes in size factor, electron concentration and precipitation of the gamma phase. The introduction of gamma phase is helpful to improve the hot workability and ductility of NiMnGa alloy, but deleterious to the shape-memory effect. (C) 2008 Elsevier B.V. All rights reserved.