The ductility and shape-memory properties of Ni-Mn-Co-Ga high-temperature shape-memory alloys
Ma, Y. Q.
Yang, S. Y.
Liu, X. J.
- 材料学院－已发表论文 
Ni-Mn-Co-Ga alloys with Ni/Mn or Ni and Mn substituted by Co were investigated as candidates for high-temperature shape-memory alloys. Ni(56-x)Co(x)Mn(25)Ga(19) alloys with x < 8 consist of single phase martensite, whereas Ni(56-x)Co(x)Mn(25)Ga(19) (x >= 8), Ni(56)Mn(25-y) Co(y)Ga(19) (y = 4,8) and Ni(56-z/2)Mn(25-z/2)Co(z)Ga(19) (z = 4,6) alloys consist of a two-phase mixture of martensite and gamma phase. The mechanical and shape-memory properties of Ni(56)Mn(25-y)Co(y)Ga(19) and Ni(56-z/2)Mn(25-z/2)Co(z)Ga(19) alloys, which were hot-rolled into 0.5 mm thin plates by conventional hot rolling process, were investigated. The ductility and hot-workability of Ni-Mn-CO-Ga alloys were greatly improved by increasing the amount of ductile y phase. Dynamic tensile tests and scanning electron microscopy observations of fracture surfaces confirm that the existence of y phase plays a key role in improving the ductility of Ni-Mn-Co-Ga alloys. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.