High undercooling effect on magnetic shape memory Co–Ni–Ga alloys

The martensitic microstructure and crystal structure evolution of Co46Ni27Ga27 alloys under different undercooling condition was investigated. The increase of reverse martensitic transformation temperature was found with undercooling in 22 to 165 °C undercooling range, but decreased with further high undercooling. The reasons for these have been discussed using the elastic strain energy mechanism and grain refinement caused by internal stress during rapid solidification.