Computer study of inter- and intragranular surface cracks in brittle polycrystals

A model was constructed that allows crack paths (and hence, for example, surface roughness) to be computed/modelled for given assemblies of real grains. Input variables are such things as the fracture energy of grain boundaries compared with the transgranular fracture energy, the proportion of special and random grain boundaries, and the influence of elongated grains present. A numbers of conclusions result from this investigation. It is shown that fracture surface characteristic become insensitive to the relative energy of fracture along grain boundaries when there is less than 60% of the fracture energy across grain interiors. Further, the result suggests a parabolic relationship between the fracture resistance of polycrystals and the percentage of special grain boundaries.