A CRITICAL REVIEW OF THE PEIERLS MECHANISM

Abstract

A thorough review is made of the application of the Peierls model to the macroscopic plastic deformation of ionic crystals, metals, alloys, and covalently bonded crystals. The effects of the shape of the Peierls hill, kink–kink energies, and the frequency terms on the stress–temperature and activation volume–stress relationships are extended and discussed. Theory is compared with experimental results, giving special emphasis to recent advances. Single-crystal data for [Formula: see text] {110} thermally activated slip in Ta and Mo at low temperatures agree well with the dictates of the Peierls mechanism. Deformation characteristics of polycrystalline Fe alloys containing either 2 wt.% Mn or 11 at.% Mo agree with expectations based on the Peierls mechanism only at temperatures below about 200 °K. At higher temperatures, the effective stress decreases more slowly and the activation volume increases more rapidly with increasing temperature than can be accounted for by the Peierls mechanism. Over this higher temperature range, however, the experimental data are in good agreement with Escaig's mechanism based on the recombination of dissociated screw dislocations. It is also shown that low-temperature [Formula: see text] {123} slip in AgMg, prismatic slip in Ag plus 33 at.% Al, and in Mg plus 6–12 at.% Li occurs by the Peierls mechanism.