Several kinds of Cu/SiO2 bicrystal, having [011] twist boundaries with differing misorientation angles, were tensile-tested at 473 to 1023K using strain rates ranging from 4.2 x 10-5 to 4.2 x 10-3/s in vacuum. Most of the bicrystals fractured intergranularly. The grain-boundary strength and fracture behavior of the bicrystals depended strongly upon the grain-boundary character, temperature and strain-rate. As the misorientation angle or grain-boundary energy increased, grain-boundary fracture took place more easily at lower temperatures; with lower fracture stresses. The fracture stress and elongation-to-fracture decreased almost monotonically with increasing temperature and decreasing strain-rate. The observed grain-boundary character and test-condition dependence of the grain-boundary strength could be understood by considering the occurrence of stress-concentration sites around the grain-boundary SiO2 particles; to form voids and cracks caused by grain-boundary sliding.

Deformation and Fracture of Cu-SiO2 Bicrystals with [011] Twist Boundaries. H.Miura, T.Sakai, H.Toda: Acta Materialia, 2003, 51[16], 4707-17