Thermal Generation of Points Defects in beta Cu-Zn-Al Alloys

A. SOMOZA; C. MACCHI; R. ROMERO

MATERIALS SCIENCE FORUM

Trans Tech Publications

Año: 1997 vol. 255 p. 587 - 589

0255-5476

The vacancy behavoir in beta Cu-Zn-Al single crystals alloys was studied by means of positron lifetime spectroscopy. Thermal equilibrium measurements were made between room temperatura and about 950K. The experimental data were interpreted in terms of the two-state standard trapping model. From the evolution of the lifetime parameters, the temperatura dependence of the vacancy concentration is obtained. Between 380K and 540K, the Arrhenius plot for the vacancy concentration exhibits the usual linear behavoir and an apparent vacancy formation energy for the CsCl-ordered type structure beta Cu-Zn-Al of 0.57eV is estimated. Between 550K and the long range order-disorder temperatura Tb2 a slight monotonic increase in the positron lifetime is observed. Above Tb2 the important increase in the average lifetime is also detected. The overall trend of the average positron lifetime is discussed