On lattice and material-frame rotations and crystal hardening in high-symmetry axial loading

Abstract

A diverse range of experimental behaviour in high-symmetry tensile loading of fcc crystals has been reported in a number of classic papers in the literature (1960–1982). This behaviour includes: (i) axis stability and axisymmetric deformation in ⟨111⟩ and ⟨100⟩ load orientations; (ii) axis rotation toward a ⟨111⟩ orientation in coplanar double-slip in ⟨110⟩ loading; and (iii) axis rotations toward (from an initial misalignment) or away from precise ⟨111⟩ and ⟨100⟩ load orientations, with a reduced number of active slip planes. In this paper extensive kinematic analyses of coincident and relative rotations among material, lattice, and loading frames in each of these orientations, together with additional kinematic solutions for load-axis rotations, are combined with experimental information and perspectives connecting relative hardening and geometric slip-system interactions to determine probable active systems and slip rates in this diverse set of experiments. It is found that a set of basic hardening inequalities, which follow from classic latent hardening experiments in single slip, is consistent with the full range of experimental behaviour in high-symmetry axial-load orientations.