Thermal formation of atomic vacancies in γ Cu–Zn

Using positron annihilation lifetime spectroscopy, the temperature dependence of the formation of thermal vacancies in the γ phase of the Cu–Zn alloy was studied. Thermal equilibrium measurements were made in situ between 135 K and about 950 K. The experimental data were interpreted in terms of the well-established positron two-state trapping model. From the evolution of the lifetime parameters between ∼400 K and ∼800 K, an Arrhenius plot for trapping rate, directly linked to the vacancy concentration, exhibits the usual linear behavior. As a result, a value for the vacancy formation enthalpy for the complex cubic structure studied was estimated at Hvf=0.46±0.03eV.