Dislocation groups, multipoles, and friction stresses in α-CuZn alloys

Characteristic features of the dislocation structure developed in the first stage of deformation of single-glide oriented crystals of concentrated f.c.c. alloys like α-CuZn are extended multipoles in the primary slip planes. Their various configurations are explained by considering their formation in the case that the dislocations destroy part of the friction stress by cutting through the effective obstacles which in this alloy are assumed to be short-range ordered clusters. This obstacle destruction mechanism which should occur quite generally in concentrated alloys favours the-development of extended dislocation groups. It is shown that in this case the original value of the friction stress may well exceed the macroscopically measured critical resolved shear stress.