Small-scale confined R-phase transformation in Ni47Ti49Fe2-Nb2 alloy

Abstract This study investigated the transformation behaviour of small-scale confined B2→R phase transformation in a Ni47Ti49Fe2-Nb2 alloy. Such confined transformation was achieved by introducing a high density of dislocations in the alloy through warm wire drawing. In contrast to the thermally induced B2→R transformation in a conventional polycrystalline matrix with a low dislocation density, where the twined R phase plates of 25 nm in width are formed, the R-phase transformation in the highly confined matrix was found to produce small twinning-free R phase particles of 5 nm in size and to form a reduced c/a ratio.