Microindentation fracture behavior of laser surface modified alumina ceramic

A high energy density continuous wave Nd:YAG laser is used for modifying the surfaces of porous alumina ceramic compacts. The increased fracture toughness of the modified surface region at higher laser fluences is associated with increased densification and coarsening of grains in the resolidified layer. The coarsening of grains offers increased resistance to the initiation and propagation of indentation cracks, as indicated by the transition in the fracture mode from predominantly mixed to predominantly intergranular with increasing laser fluence.