J. Phys. IV France
Volume 112, October 2003
Page(s) 487 - 493

J. Phys. IV France
112 (2003) 487
DOI: 10.1051/jp4:2003931

Origin of two way shape memory effect in Cu-based shape memory alloys

X.M. Zhang1, 1, J. Fernandez1 and J.M. Guilemany1

1  Institute of Metal Research, Chinese Academy of Sciences, 110015 Shenyang, China

Two-way shape memory effect (TWSME) should be trained by thermomechanical cycling or constrained aging. After constrained aging, oriented stress fields around precipitates and stabilized stress-induced martensite were found in Cu-Zn-A1 alloys. The effect of these phases on TWSME has been studied by in-situ observations in TEM. For thermomechanical cycling, paired dislocation bands and oriented microstrain in re-oriented martensite were studied by molecular dynamics simulation. It was found tliat the oriented stress fields of the precipitates, pair dislocation bands and re-oriented martensite also have two-way memory effect during forward and reverse transformation. These stress fields can be termed two-way memory stress fields (TWMSF). The TWMSF contribue their stress fields to the formation of the preferential martensite variants that give raise the TWSME.

© EDP Sciences 2003