Thermal formation of atomic vacancies in γ Cu-Zn

C. MACCHI; R. ROMERO; A. SOMOZA

SCRIPTA MATERIALIA

Elsevier

Año: 2006 vol. 54 p. 437 - 440

1359-6462

Using positron annihilation lifetime spectroscopy, the temperature dependence of the formation of thermal vacancies in the gamma 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 atHf = 0.46 +- 0.03 eV