Ea. Holm, SURFACE FORMATION ENERGY FOR INTERGRANULAR FRACTURE IN 2-DIMENSIONAL POLYCRYSTALS, Journal of the American Ceramic Society, 81(3), 1998, pp. 455-459
A global energy minimization method for calculating intergranular frac
ture surfaces which minimize surface formation energy was developed us
ing standard graph algorithms, The intergranular fracture of equiaxed,
single-phase, polycrystalline grain structures was examined under a v
ariety of energetic conditions. In energetically isotropic systems the
minimum energy fracture surface has length 1.1 times the sample width
independent of grain size, A criterion for fracture mode was derived
for this case. Using a ball-and-spring model, local mechanical effects
were found to increase fracture length by at most 5% in isotropic sys
tems, The presence of typical low-energy, low-angle grain boundaries m
inimally affects intergranular fracture path, but may alter the prefer
red fracture mode, In systems with randomly dispersed, very weak bound
aries (i.e., micro-cracks), fracture surfaces veer to follow low surfa
ce formation energy boundaries, resulting in tortuous, low-energy frac
ture paths, and intergranular fracture is strongly preferred.