The behaviour of random high-angle grain boundaries of a Pb-based alloy during thermo-mechanical processing and heat treatment was studied using the electron back-scattered diffraction method. Repetitive thermo-mechanical processing was found to be effective in increasing the fraction of special boundaries, and this was attributed to the ∑3 boundaries which were associated with annealing twins. Evidence was found that the dissociation of fast moving random high-angle boundaries into ∑3 boundaries correlated with other random boundaries. Also formed during intermittent thermal exposure were ∑3n networks, which evolved mainly into ∑3 boundaries of lower energy. The present results thus supported the so-called growth-accident model for annealing-twin formation. Viable thermo-mechanical treatments were proposed for promoting special boundaries.

Direct Observation of Annealing Twin Formation in a Pb-Base Alloy. K.H.Song, Y.B.Chun, S.K.Hwang: Materials Science and Engineering A, 2007, 454-455, 629-36