Brittle vs ductile fracture behavior in ceramic materials at elevated temperature

An intergranular crack initiated at a pore located in a triple junction of grain boundaries in a ceramic material is considered in order to investigate the brittle versus ductile fracture in different temperature ranges. The critical fracture stress and critical dislocation slip stress are estimated in dependence on temperature for the case of Al₂О₃ ceramics. The temperature dependless local stresses in vicinity of blunt cracks and a triangular-shaped pore are calculated by the finite element method. The provided analysis reveals the favorability of the fracture scenarios upon the temperature conditions and bluntness of a crack tip as well.