The response of yttrium aluminum garnet (YAG) grains and grain boundaries to nanoindentation

A systematic investigation on the mechanical response of the interior grain and grain boundary of yttrium aluminum garnet is carried out using nanoindentation and microstructure characterization. The nano-hardness is calculated, while the residual indent is analyzed in terms of surface profiles, plastic deformation and elastic recovery. The results show that the nano-hardness at the center of grain is higher than that in the grain boundary region. All indents display an anisotropic elastic recovery, mainly occurring in the loading direction. The grain boundary has a better plasticity than the center of grain, which is probably due to a weaker inter-atomic bonding force at the grain boundary rather than the formation of glassy phase at intergranular region. In addition, indentation size effect in the center of grain and at grain boundary region are determined by the analysis of nano-hardness using Meyer's law. A weaker indentation size effect in the grain boundary region is observed due to a smaller elastic recovery.