WEAK-BEAM STUDY OF THE DISLOCATION MICROSTRUCTURE OF BETA-CUZN DEFORMED IN THE TEMPERATURE DOMAIN OF THE PLASTIC ANOMALY

In the general framework of studies of the anomalous increase in plastic strength with temperature which is common to a number of ordered alloys, the effect of test temperature on the deformation microstructure has been investigated in beta-CuZn (B2 structure). Single crystals have been deformed in compression at different temperatures between room temperature and 200-degrees-C along axes near [001] and [111BAR]. The deformation microstructure has been observed under weak-beam conditions. The superdislocations with Burgers vector a<111> dissociated into two superpartials bounding an antiphase boundary (APB) have been found to dominate the microstructure over the whole temperature range although, in the near [111BAR] orientation of the applied stress, deformation involves glide in the a<001> direction at the peak temperature. The relative density of climb-dissociated dislocations with mixed character has been observed to increase with temperature. In addition, the energies of the APBs on {110} and {112} planes have been measured at room temperature.