MECHANISM OF FORMATION AND MECHANICAL-BEHAVIOR OF TILT GRAIN-BOUNDARIES

It is shown for NaCl crystals that the damping character of dislocation unpinning, motion, and multiplication during different tests (at stress rates sigma approximate to 10(-4) to 35 MPa s(-1) and in the temperature range T approximate to (10(-3) to 0.945) T-m, T-m melting point) inevitably leads to consecutive formation of subgrain walls, cells, and grain boundaries under growing sigma. The scaling behavior of dislocation mean paths at multiplication, their spacing in slip lines and various high density dislocation structures versus the reciprocal of applied stress confirms the prevailing role of dislocation cross-slip, climb, and the Orowan bowing mechanisms in the evolution of deformation structures in different crystal classes.