The Crystallographic Aspect of the Mechanical Twinning in Ti and α-U

A crystallographic study on the mechanical twinning in Ti and α-U is made by a method similar to that in a previous paper, allowing more kinds of atom movements, and the twin elements, K 1 , K 2 , η 1 and η 2 , are determined. It is found that {1122} and {1124} twins in Ti are reciprocal to each other and that the elements of {1121} twin are in agreement with Hall's result. It is also found that a general result that a plane having the smallest shear S is liable to twin in order nearly holds in Ti and α-U.