J. Phys. IV France 112 (2003) 1017
Development of the Co-Ni-AI ferromagnetic shape memory alloysK. Oikawa1, T. Omori2, Y. Sutou2, R. Kainumal1 and K. Ishidal1
1 National Institute of Advanced Industrial Science and Technology, 4-2-1 Nigatake, Miyagino-ku, Sendai 983-8551, Japan
2 Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 02, Sendai 980-8579, Japan
Ferromagnetic shape memory alloys have been developed in the Co-Ni-AI temary system with two-phase structure. The (B2) phase of the Co-33Ni-27Al and Co-34Ni-28Al alloys exhibits both paramagneticlferromagnetic transition and a thermoelastic martensitic transformation from to (L1 0). The microstructure of both alloys shows the primary phase surrounded by the (A1) phase which brings about the drastic effect in the improvement of the hot workability. By annealng in the two-phase region after solution treatment, the phase precipitates along grain boundaries in the phase, besides in the grain. The alloys annealed at 1273 K showed a good cold workability and a thermal activated shape memory effect. These ferromagnetic and ductile shape memory alloys are very promising for one of the new smart matenals.
© EDP Sciences 2003