Structural characterization of a special boundary between α plates after martensitic transformation in cobalt

•The special misorientation relationship (71.4°/<112̅0>) between α plates in Co after martensitic transformation is the common misorientation relationship.•The interfacial structure of such special boundary consists of 0001//101̅1 basal–pyramidal interfaces and steps.•The special boundary arises from the {111} planes in FCC phase.

In this study, the interfacial structure of a special boundary between α plates in cobalt after martensitic transformation was characterized and investigated in detail, by using transmission electron microscopy (TEM) and high-resolution TEM. It was found that the boundaries with the special misorientation (71.4°/<112̅0>) consist of 0001//101̅1 basal–pyramidal interfaces and steps. This special misorientation relationship (71.4°/<112̅0>) between α plates should be identified as one common misorientation relationship.