Effect of twins on the crystallographic characteristics of the Mg17Al12 phase in the pre-compressed AZ91 alloy

beta Crystallographic characteristics of the beta-Mg17Al12 phase have been investigated in the pre-compressed and aged Mg-9.0 wt%Al-1.0 wt%Zn alloy. Due to pre-compression, morphologies of the beta phases became much wider and shorter. The aspect ratio was reduced dramatically. Besides, octahedron shaped beta phase with Crawley OR have been observed and portion of the beta phase with Crawley OR increased. The twins generated by compression affect the ORs of the beta phase. The OR between the beta particle and the {10-12} twin is: [1-210](alpha)//[11 -1](beta), (0002)(alpha) near parallel to (1-2-1)(beta). ORs between beta particles and the {10-11} twin were more complex. Two typical ORs between the beta particles and the {10-11} twin have been identified as: [1-21-3](T)//[110](beta 1), (1-101)(T)//(3 -30)(beta 1) and [1-21-3](T)//[113](beta 2), (0-111)(T)//(21-1)(beta 2), which have rarely been reported before. (C) 2018 Elsevier B.V. All rights reserved.