Features of Highly Twinned Microstructures Produced by GBE in FCC Materials

Abstract

The proportion of low ΣCSL boundaries of single phase brass, Ni based Alloy 690, 304 stainless steel and Pb alloy were enhanced to about 70% (according to Palumbo–Aust criterion) which mainly were Σ3n (n = 1, 2, 3…) types by small amount of deformation and recrystallization annealing. All the resulting microstructures were constituted of large size grain-cluster, in which all the orientation relationships between any two grains (no matter adjacent or not) could be described by Σ3n misorientations according to twin chain analyzing. Twin relationships up to 8th generation (Σ38) were found in one of such clusters. The outer boundaries of grain-clusters were crystallographically random with the adjacent clusters. In the case of high proportion of low ΣCSL boundaries, the connectivity of random boundary network was not fragmented obviously when the Palumbo–Aust criterion was used, whereas substantially interrupted when the Brandon criterion was applied.