The Influence of Carbon and Oxygen in the Grain Boundary on the Brittle--Ductile Transition Temperature of Tungsten Bicrystals

The brittle--ductile transition temp. (BDTT) range of oriented tungsten bicrystals with varying concentrations of carbon and oxygen was determined. The brittle temp. range was decreased by C and increased by O. The temp. shifts are more pronounced for the higher misorientation grain boundaries. Carbon increases the grain boundary cohesion, O decreases this cohesion, compared with the purified state. The intrinsic intergranular brittleness of W is slightly modified by C and O whose local concentration depends upon the boundary structure. 10 ref.--J.H.B.