Further observations of anomalous slip in niobium single crystals

Abstract

Investigation results show that anomalous slip in Nb monocrystals is an athermal process. It is also possible that a small amount of prestrain at room temperature is a prerequisite for anomalous slip. Results indicate that the phenomenon occurs predominantly in a very small temperature range, i.e., 50 to 90/sup 0/K. It is most predominant at 77/sup 0/K. It is possible that anomalous slip occurs at other temperatures, which would account for the variations in the yield stress found at lower temperatures. If anomalous slip does occur by an athermal process, then it is possible that anomalous slip occurs by the motion of edge dislocations, because the intrinsic lattice resistance of edge dislocations is assumed to be very small. (JRD)