Glide Properties and Dislocation Structure of β-brass Single Crystals

Single crystals of ordered β-brass with three different crystal orientations were deformed in tension and compression at 77, 175 and 300 K, and the operative slip systems and the dislocation structures were studied. The glide behavior and yield stress were strongly dependent on the crystal orientation, deformation temperature and the sense of applied stress. Above 175 K, only the {110} 〈111〉 system was observed as the operative slip system, regardless of crystal orientations and the sense of the applied stress. At 77 K, the slip in the twinning [111] direction on a {112} plane took place as the most preferred slip system, while the slip in the antitwinning [111] direction was observed only in the compressed specimen with the orientation near [001]. The critical resolved shear stress for the {110}〈111〉 slip system hardly showed the temperature dependence between 175 and 300 K in both tension and compression tests. The critical resolved shear stress for slip in the antitwinning direction on a {112} plane was 1.7 times higher than that in the twinning direction on the same plane. The dislocation structures on a {110} plane consisted of zig-zag shaped, very long mixed dislocations at 175 and 300 K . In addition, these dislocations frequently formed quite long dipoles. On the {112} plane, numerous segments of screw dislocations were markedly noticed. In the case of slip in the twinning direction, a large number of isolated short dipoles of mixed dislocations and of the dotted small loops were found, whereas in the case of slip in the antitwinning direction, jogs on the screw dislocations, debris loops and large loops were most frequently observed.