Crystallography of Mg 2 Sn precipitates with two newly observed orientation relationships in an Mg–Sn–Mn alloy

Two new orientation relationships between β-Mg₂Sn precipitates and α-Mg matrix have been observed by transmission electron microscopy. One is (1 1 0) _β //(0 0 0 1) _α , [0 0 1] _β //[1 −1 0 0] _α , and the other is (1 1 0) _β //(0 0 0 1) _α , [−1 1 −1] _β //[1 −1 0 0] _α . The precipitates with both orientation relationships exhibit a lath shaped morphology, with the long axis lying along [1 1 −2 0] _α . The morphology is interpreted by a three-dimensional near coincidence sites model.