A special single variant zone in directionally solidified Ni-Mn-Ga alloy

Abstract Three distinct structures comprising self-accommodated solid zone, (110)M preferred oriented liquid zone and (001)M oriented single variant zone were discovered in directionally solidified Ni-Mn-Ga alloy rod. The preferred (110)M orientation in liquid zone directly causes a special single variant zone to form around quenching interface. It is attributed to a longitudinal, suddenly-shrinking lattice, produced in the liquid zone after martensitic transformation, which induces a tension force at the joint. A tensile test simulates and validates the formation of single variant induced by inner force. A mechanism of variant formation is described in the present study, too.