Annealing Twins in Pure Aluminum

Abstract

While aluminum is perhaps one of the most commonly available pure fee metals, it is relatively unresearched with regard to grain boundary energetics. By comparison with other fcc pure metals, annealing twins are rarely observed in Al. and annealing twin bands identified by two parallel {111} planes separating a twinned crystal portion from matrix grain - while common to essentially all other fcc pure metals - have never been unambiguously observed in pure Al. Additionally, grain corner twins prominent in other fcc metals (and alloys) and consistent with the twin- formation theory of Fullman and Fisher, have never been observed in g pure Al. Finally, of all the studies of Al grain boundary structures cited only the work of Sargent employed the techniques of transmission electron microscopy and selected-area electron diffraction to identify the twinning plane as (111).