Unveiling the Twinning Mechanisms in Al2MgCu: Insights from Electron Backscatter Diffraction Analysis in High Alloyed Al-Zn-Mg-Cu Alloys

This study explores the twining phenomenon in the Al2MgCu intermetallic compound, a common second phase in a hot-rolling high-alloyed Al-Zn-Mg-Cu alloy, using advanced electron backscatter diffraction (EBSD). Theoretically, the full twining elements of types I {110} < -1, 1, 2.9197 > twining system in Al2MgCu with an orthorhombic structure (space group cmcm) are first determined. There are two possible {1 1 0} twin variants, which are (1 1 0) [-1, 1, 2.9197] and (-1 1 0) [-1, -1, 2.9197], or crystallographically equivalent (-1 -1 0) [1, -1, -2.9197] and (1 -1 0) [1, 1, -2.9197]. The misorientation between a {1 1 0} twin and matrix Al2MgCu grains has been calculated to be [0 0 1] 44.3 degrees, which can be used to identify {1 1 0} twins in Al2MgCu by EBSD.