Grain boundary precipitation induced by grain crystallographic misorientations in an extruded Al-Mg-Si-Cu alloy

The grain boundary precipitation induced by grain crystallographic misorientations in an extruded Al-Mg-Si-Cu alloy was investigated by electron back-scattering patterns and high resolution transmission electron microscopy. The results showed that compared with the recrystallization cube {1 0 0}〈0 0 1〉 texture, the deformation brass {1 1 0}〈1 1 2〉 texture prevailed in the microstructure. The brass texture mainly contributed for the formation of low angle grain boundaries, where the pre-β″/β′ phases were formed during precipitation. The recrystallization cube texture predominately induced the formation of high angle grain boundaries, where the Q′/Q phases related to the corrosion were precipitated. And, high and low grain boundary was 23.5% and 76.5% proportion in the microstructure, respectively. Finally, it was believed that in order to improve the resistance to intergranular corrosion of alloy, the recrystallization cube {1 0 0}〈0 0 1〉 texture should be inhibited as far as possible.