Crystallographic orientations of intermetallic compounds of a multi-pass friction stir processed Al/Mg composite materials

The crystallographic orientation relationships between intermetallic compounds and matrices were investigated in the interface of an overlapped multi-pass friction stir processed Al/Mg composite materials. During the friction stir processing, an Mg rich intermetallic compound (gamma-Al12Mg17) was formed close to the bottom Mg alloy and an Al rich intermetallic compound (beta-Al3Mg2) was formed close to the top Al alloy. Two new orientation relationships between the Mg matrix and the gamma-Al12Mg17 were observed and analyzed. One was identified as [01 (1) over bar2] (Mg)//[(1) over bar 01](gamma), (0 (1) over bar 11)(Mg)//(101)(gamma), and the other one was identified as [1 (2) over bar 10](Mg)//[531](gamma), (0001)(Mg) 1.7 degrees form ((1) over bar2 (1) over bar)(gamma). The stereographic projections of two new orientation relationships were calculated and discussed. Moreover, high resolution transmission electron microscopy studies of the interface between the Mg matrix and the gamma-Al12Mg17 indicated that the gamma-Al12Mg17 had a coherent interface with the Mg matrix. It was also observed that the beta-Al3Mg2 had a cubic-to-cubic orientation relationship with the Al matrix in the Al/Mg composite material interface. (C) 2017 Elsevier Inc. All rights reserved.