Deformation behavior and dislocation structure of CuAu ordered alloy

An ordered CuAu alloy, which had relatively coarse grains (5 to 10 mu m), without the lamellar structure, is mechanically tested at temperatures from 77 to 658 K. The temperature dependence of the yield stress is shown to be anomalous with a maximum near T(p)approximate to 573 K. The TEM analysis reveals the presence of single dislocations, superdislocations and microtwins. Long rectilinear dislocations at 523 K are identified as blocked screw superdislocations with the Burgers vector type <101]. Numerous curved single dislocations are seen, but blocked single dislocations are not detected. Various models are discussed to account for the specific deformation behavior of the ordered CuAu alloy.