Deformation band formation, characteristics, history

Abstract

Deformation bands (DMB) are crystal slabs that develop slip on systems different from neighbours; they rotate in different directions developing intervening transition boundaries (TB) that rise rapidly in misorientation. In polycrystals, grains divide into DMB, slipping on 2 or 3 systems to provide the 5 required components with minimum energy, as confirmed through OIM boundary misorientations and band rotation poles. TEM exposed the subgrains but seldom TB, except in single crystals as layers of cells. As the TB extend and align into layer bands, the microtextures are similar in cold and hot working. In hot working, TB are quite narrow and able to migrate; at large strains, lengthening and rotating TB (like grain boundaries) are responsible for rapid accumulation of high angle facets of many subgrains. Nevertheless sub-boundaries persist defining steady-state cellular dimensions and flow stress. © 2010 IOP Publishing Ltd.