THE PLASTIC-DEFORMATION OF 18R LONG-RANGE ORDERED CU-ZN-AL SINGLE-CRYSTALS - THE TEMPERATURE AND STRAIN-RATE DEPENDENCE OF THE CRITICAL STRESS AND THE INFLUENCE OF DYNAMIC STRAIN-AGING

Long-range ordered (18R structure) Cu-Zn-Al single crystals with the s tacking sequence ABCBCACAB of close packed planes have been plasticall y deformed in compression. The dislocations move on the basal plane an d have the shortest possible translation Burgers vector. The critical resolved shear stress increases with temperature above room temperatur e and the strain rate sensitivity decreases, reaching negative values at elevated temperatures. The results cannot be explained by an increa sed friction stress of the moving dislocations due to diffusion induce d reordering of the antiphase boundary between the partials. It is ins tead suggested that diffusion modifies the dislocation configuration, essentially after it gets immobilized at obstacles. (C) 1997 Elsevier Science S.A.