Edge-on-impact response of a coarse-grained magnesium aluminate spinel rod

Edge-on-impact tests utilizing spherical steel balls were conducted in order to observe deformation and fracture behavior of magnesium aluminate spinel rods. The ensuing damage evolution was captured using a high-speed camera while an analysis of fracture modes was accomplished by post mortem inspections of recovered debris/fragments. Conclusive evidence of a shift from transgranular to intergranular fracture mode was uncovered as the damage front depth increased from the impact site. Recovered ball fragments revealed a high level of erosion between the ball and the fragmented materials during initial contact and subsequent ejection of the fragments. Finally, the energy dissipation mechanisms of various deformation modes during impact were analyzed and the contribution of each to the total impact energy dissipation is quantified using analytical equations available in literature. The formation of a 3-dimensional network of mixed mode fracture, grain ejection and frictional erosion were identified as the most significant inelastic mechanisms responsible for energy dissipation during impact events in magnesium aluminate spinel.

► Dynamic indentation hardness and intergranular and transgranular fracture modes.
► High velocity impact damage and quantification of energy dissipation modes.
► Mixed mode fracture, grain ejection and frictional erosion in Spinel.