The Role of the Grain Boundary in the Deformation of Ceramic Materials

摘要

The effect of solute additions on the deformation and fracture behavior of KCl bicrystals was investigated. This material exhibited a definite transition from brittle to ductile fracture, the brittle type being of an intergranular nature and the ductile a necked matrix failure. This transition temperature was about 175 C for the high purity specimens and 400 C for tilt misoriented calcium doped (100 ppm) bicrystals. Calcium doped twist boundary bicrystals showed intergranular brittle fracture at temperatures as high as 600 C, which was the highest test temperature examined. It was found that wavy glide rather than the planar type was a prerequisite for ductile behavior and that the role of the solute was to suppress the onset of wavy glide, thus elevating the transition temperature. The data also showed a greater propensity for grain boundary sliding in the doped material in the tests which were conducted above the transition temperature. (Author)