Investigation of the activation-parameters of low-temperature slip in cubic metals

The macroscopic critical resolved shear stress (CRSS) tau of 9 body-centred cubic (BCC) and 5 face-centred cubic (FCC:) metals has been found to vary with temperature Tin the range 0 to 300 K as given by: In tau = A - BT, whe re A and B are positive constants. The tau-T data have been analysed within the framework of a kink-pair nucleation (KPN) model of plastic flow in cry stals. The microscopic parameters of the unit activation process of yieldin g, e.g. the initial length of the glide dislocation segment, the critical h eight of the kink-pair nucleated in it, the activation volume associated wi th the CRSS, and the binding energy per interatomic spacing along the glide dislocation in the slip plane etc., have been evaluated. A consistent pict ure of the dislocation kinetics involved in the yielding of BCC and FCC met als emerges, which is adequately described by the KNP model of plastic flow in crystals.