INTERNAL FRICTION ASSOCIATED WITH HIGH-TEMPERATURE DISLOCATION MOBILITY

Abstract
Internal friction associated with dislocation mobility can be classified into three catagories : (1) Those originated from the intrinsic properties of single dislocations ; (2) those originated from the interaction between dislocations and point defects ; (3) those originated from dislocation climb and from the coorperative behavior of groups of dislocations (e.g., dislocation pileups, grain boundaries, subgrain boundaries, etc.) which give rise to relaxation phenomena only at higher temperatures. It seems, thus, the topic of internal friction associated with high temperature dislocation mobility (Theme 3) should include catanory (3) and part of catagory (2) concerning with the dislocation-point-defect interaction at high temperatures. The term "high temperature" used here may be defined as the range of temperature at wich the pinning points or "atmosphere" concerned are "mobile" and migrate with dislocations. The papers of Theme 3 may be discussed under the following headings : I. Mobile pinning points migrating with dislocations ; II. dislocation pileups and dislocation climb ; III. grain boundary relaxation ; IV. high temperature properties of solids related to dislocation mobility at high temperatures. Various models and viewpoints have been proposed by different authors and it is highly interesting to start a critical discussion.