Interaction between a dislocation and impurities in KCl doped with Li+ or Na+

Abstract

A strain-rate cycling test during the Blaha effect measurement was carried out in stage I, II and III of stress-strain curve at 80–300 K. On the basis of the relation curve of strain-rate sensitivity and stress decrement due to oscillation, the influence of strain on the interaction between a dislocation and impurities was investigated for KCl : Li+ (0.5 mol% in the melt) and KCl : Na+ (0.5 mol% in the melt). It has been so far reported that the curve seems to reflect the influence of ultrasonic oscillation on the dislocation motion on the slip plane containing many weak obstacles such as impurities and a few strong ones such as forest dislocations. As a result, it seemed that the Na+ ions in KCl : Na+ contribute to dislocation multiplication in the three stages, whereas the Li+ ions in KCl : Li+ did not contribute to it. Furthermore, the effective stress due to the impurities decreased with increasing strain at almost all the temperatures for KCl : Na+. Accordingly, the critical temperature, at which the effective stress is zero, was larger in stage I, compared with that in stage II for KCl : Na+ from the dependence of effective stress on the temperature.