This mechanism was studied with regard to stress anomalies in Be and TiAl. The mechanism accounted for the jerky motion of highly cusped dislocations which still remained aligned along the screw direction. The stress anomaly arose directly, without making arbitrary assumptions, from a competition between thermally activated pinning and subsequent unzipping. The statistical approach showed that the exact nature of the mechanism which controlled the motion of screw dislocations was not of primary importance but that, in agreement with recent models, super-kinks played an essential role. Above a critical temperature, the dislocations were definitively locked and were unavailable for deformation when they were supplied with a configuration of pinning points in which no screw segment was present. Under creep conditions, this exhaustion process led to a decreasing strain rate. Under a constant applied strain rate, a further increase in the external stress was required in order to meet the applied strain rate; thus yielding a stress anomaly.

F.Louchet, B.Viguier: Scripta Metallurgica et Materialia, 1994, 31[4], 369-74