Migration Enthalpy of Thermal Vacancies by Positron Spectroscopy

The trapping of positrons at vacancy site in some materials provide a new and sensitive method for the equilibrium determination of point defect migration enthalpy. Data are presented for commercial Al--Mg alloys and fitted to a model allowing presentation in the form of Arrhenius plots, hence the migration enthalpy H_iv^m can be determined by the positron annihilation lifetime technique. The results show that the value of H_iv^m increases as the concentration of Mg increases.