GRAIN BOUNDARY SELF AND IMPURITY DIFFUSION IN TUNGSTEN IN THE TEMPERATURE RANGE OF ACTIVATED SINTERING

Abstract

Grain boundary self- and 57Co impurity diffusion were measured in sintered tungsten on a large temperature interval. Additionally the diffusion of 185W was investigated in Ni-doped tungsten grain boundaries in the context of the activated sintering process. In al1 three cases an unusual discontinuity was obseved in the Arrhenius plot occurring around 1370 K with quite different magnitudes for self and impurity diffusion. The results were discussed in terms of the grain boundary phase transition model of Militzer and Wieting.