Investigation of the Diffusion Mechanism of ~(57)Co Atomic Probes at the Grain Boundary Core, Segregation of ~(57)Co at Grain Boundaries and Measurement of the Diffusion Parameters of ~(57)Co Outside of the Grain Boundary Core in Polycrystals of Ta, W and

摘要

A new method [1-3] developed for the study of intercrystallite diffusion in polycrystals was used to obtain earlier unavailable information about regular features of this phenomenon and to measure earlier inaccessible parameters determining those regular features. The diffusion mechanism of the small radius atomic probe ~(57)Co in the grain boundary core of polycrystalline Ta and W is interstitial and in the grain boundary core of polycrystalline Cr is via vacancies. In poly-Cr and poly-W atomic probe ~(57)Co segregated at grain boundaries, but in poly-Ta it ntisegregated In poly-W the stationary region of high concentration of point defects disappear at low temperatures and cause new phenomena - the expansion of the region of high concentration of point defects localized near grain boundary.