Revealing the interface structure of {111} type I twin in Ti-Ni-Hf shape memory alloy composite

Abstract In the present study, the interface of martensite twins in Ti-Ni-Hf shape memory alloy composite was studied by high resolution transmission electron microscopy in terms of atomic structure. The results reveal that two varieties of interface structure for {111} type I twins are observed, which is determined by the interior substructure (001) compounds twin. The formation of {111} type I twins can be attributed to the interaction between the misfit dislocations on (001) plane and ( 1 ¯ 11) twin boundary. In addition, the corresponding characteristic parameters of misfit dislocation were calculated in theory. The theoretical value of disregistry factor and average spacing for the misfit dislocations are well in good agreement with the experimental results.