The room temperature annealing kinetics of stacking faults in cold worked alpha brasses

The room temperature annealing kinetics of stacking faults in cold worked alpha brasses were investigated by an X-ray diffraction technique. It was observed that the stacking fault probability in Cu-10 Zn alloy increases as a logarithmic function of time. This phenomena is associated with the segregation of zinc atoms to stacking faults. The ther mo mechanically treated (CW at RT, +720 h at RT, +18 h at 423 K and WQ) Cu-10 Zn alloy and also the Cu-20 Zn alloy showed an “abnormal narrowing” of stacking faults at room temperature. In order to explain this behavior, it was postulated that the partial dislocations relax under the action of the depleted area left behind them. In the Cu-30 Zn alloy the stacking fault probability showed a logarithmic decrease with respect to annealing time. This was interpreted as the relaxation of partial dislocations into their minimum energy configuration under the uniform solute impedance effect. A thermodynamic treatment of segregation to stacking faults was advanced for real multi-component solid solutions. The segregation of zinc atoms to the stacking faults in alpha brasses was calculated as a function of composition at room temperature using an IBM-360 computer. It was found that the maximum segregation to the stacking faults occurs in the Cu-6 Zn alloy.