The microstructure of martensite in a Ti50.2Ni29.8Cu20 shape memory alloy ribbons

Microstructure of martensite in Ti50.2Ni29.8Cu20 shape memory alloy (SMA) ribbons has been studied by means of transmission electron microscopy (TEM). The Ti2Ni particles and Guinier-Preston (GP) zones are observed in the ribbons annealed at 773 K for 1 h. Fine subgrains surrounded by nano-scale Ti2Ni particles exist in the interior of martensite plates. The tensile deformation mechanisms of the present ribbons mainly involve the reorientation and the detwinning of the B19 martensite twins.