POSITRON LIFETIME SPECTROSCOPY IN QUENCHED BETA-CU-ZN-AL

In the range of 293 and 1073 K, the quenching temperature dependence of positron lifetime parameters in monocrystals of a beta-Cu-Zn-Al alloy is investigated. This range covers the critical ordering temperatures T(B2) and T(L2)1. In these experiments, the quench introduces different kinds of defects into the beta-phase especially, mobile defects at room temperature. Data treatment in terms of the two-state standard trapping model shows that the concentration of frozen-in defects does not monotonously increase with the quenching temperature. Instead, a maximum near T(q) almost-equal-to 600 K appears.