Peierls stress for [ll2h](hhl) shear in the FCC lattice

Abstract

Data on the orientation of bands of nonoctahedral shear in Ni3Fe single crystals upon compression in the [001] direction are discussed within the model of crystons - carriers of shear of the superdislocation type. The discussion is based on the model of the core of the cryston as a carrier of simple shear in a deformation band of finite thickness. A concept of the Peierls stress for a cryston, τP,cry, is introduced, which is an analog of the Peierls stress τP for a single dislocation. A formula is suggested for estimating τP,cry in the case of shear on (hhl) planes. The τP,cry dependence on the indices h and l is discussed. It is shown that, in the spectrum of observed orientations (hhl), the greatest value of τP,cry corresponds to the orientation (23 23 25) of the shear-band boundary, which is the first to arise in the course of deformation (at ε = 9%). Based on the assumption on the closeness of the stress τ that corresponds to the beginning of the formation of a band with (23 23 25) boundaries to τP,cry for crystons that form this band, the width of the core of the partial dislocation that enters into the cryston core is estimated.