Quenching and Annealing of Lattice Vacancies in Pure Silver

Abstract

Quenching and annealing experiments on 99.998% pure silver lead to the following results: The energy required to form a lattice vacancy is 1.10±0.04 eV. The activation energy required to move a lattice vacancy is 0.83±0.05 eV. In specimens quenched from above 600°C most of the defects observed annealed with an activation energy of 0.57±0.03 eV. Pulse heating breaks up the 0.57-eV defect; at least one of the fragments thus produced is a single vacancy having migration energy 0.83±0.05 eV. It is suggested that the 0.57-eV defect is a divacancy. The pulse heating establishes the binding energy of the 0.57-eV defect to be 0.38±0.05 ev. Upon annealing a quenched specimen below 0°C the 0.57-eV defect anneals by second-order kinetics. Upon annealing a quenched specimen above 90°C one observes a fast annealing (approximately first order with energy of motion 0.60±0.06 eV) followed by a slow annealing process having energy of motion 0.80±0.1 eV. It is suggested that above 90°C the 0.57-eV defect does not cluster, but migrates to dislocations. The fact that below 0°C the 0.57-eV defect forms clusters, whereas above 90°C it does not, leads to a binding energy for quadrivacancies of 0.30±0.08 eV.