Self-accommodation in Ti–Nb shape memory alloys Original Research Article

Self-accommodation morphology of the image martensites in Ti–Nb shape memory alloys with Nb content ranging from 20 to 24 at.% was investigated. Hollow and solid triangular morphologies consisting of three image variants were found to be the image self-accommodation morphologies. The image variants are related to each other by twinning on image. A V-shaped morphology consisting of two image variants coupled with a solid triangular morphology consisting of three image variants was found to be another type of self-accommodation morphology. The image variants from the V-shaped morphology are related by twinning on image, whereas the image variants from the solid triangular morphology are related to each other by twinning on image. Pairs of crystallographically equivalent image twinning dislocations with steps of opposite signs were found to cause the overall orientation of the twinning terraces and steps to be parallel to the image twinning interface.