Rapidly directional solidification of highly undercooled Ni–Fe–Ga shape memory alloy melts

In the present work, high undercooling rapid solidification technique is applied to the directional crystal growth of ternary Ni–Fe–Ga shape memory alloys (SMAs). Experimental results show that the phase selection of undercooled melts strongly depends on the triggering mode and nucleation undercooling. With the planar triggering nucleation at the undercooling of 160 K from the bottom of alloy melt, a directionally solidified sample with a preferred (2 0 0) orientation of γ phase is obtained. When the point triggering mode is employed at 180 K, γ phase is suppressed completely and the directionally solidified sample demonstrates almost identical phase transformation temperatures.

► High undercooling rapid solidification technique is an effective and feasible way to fabricate directional Ni–Fe–Ga shape memory alloys.
► The phase selection of undercooled melts strongly depends on the nucleation triggering mode and nucleation undercooling.