Transmission electron microscopy of antiphase boundary-like structure of B19 ' martensite in Ti-Ni shape memory alloy

An antiphase boundary (APB)-like structure of the B19' martensite in Ti-Ni alloy was investigated by transmission electron microscopy The APB-like structure shows atomic shifts on both the (0 1 0)B19' plane along the c-axis and the (0 0 1)1319, plane along the b-axis, a kind of ledge-and-step structure on the b-c plane, in addition to a displacement along the a-axis The displacement vector can be expressed as R = <-0 1648 1/2 0 4328 > in terms of the conventional atomic coordinates of Ti and Ni in the B19' martensite The APB-like structure is not inherited from APB in the B2 parent phase We conclude that the APB-like structure is developed by accidental impingement of differently nucleated martensitic domains during the transformation This structure is defined as a kind of stacking fault with an APB-like contrast (C) 2010 Acta Materialia Inc Published by Elsevier Ltd All rights reserved