The influence of zener pairs on the temperature dependent component of the critical flow stress of silver based solid solution crystals

Abstract

At low temperatures (below about 1 3 of the melting point temperature) the critical flow stress of solid solution crystals is composed of two components: 1. (1) A temperature independent stress component, which is due to the solute atoms. The solute atoms are defects that have the symmetry of the matrix. As shown previously this kind of defect leads to a temperature independent stress component. 2. (2) A temperature dependent stress component, which is assumed to be due to Zener dipoles. Zener dipoles have a lower symmetry than the matrix. The assumption that Zener dipoles are responsible for the temperature dependent component of the flow stress is tested with the help of published flow stress data of Ag-In and Ag-Zn alloys and a modified Fleischer theory for thermally activated glide. It is possible to determine the concentration, the concentration dependence and the dipole strength of the defects. A comparison of the characteristic data of the Zener dipoles obtained from the flow stress analysis to the data obtained from the internal friction measurements shows good agreement of the dipole strength and especially the concentration dependence of the Zener dipoles. This result demonstrates that the temperature dependent flow stress component in solid solution crystals can be due to the presence of Zener dipoles.