Detection of residuai stresses in glass-penetrated polycrystalline alumina with nanoindentation

Silicate glasses were introduced into polycrystalline alumina specimens by controlled penetration. Mechanical properties of intergranular phases thus formed were probed with nanoindentation and in-situ atomic force microscopy. The approach makes it possible to locate indentations on particular regions of the sample to measure both the hardness and Young’s modulus of the glass contained at interfaces and in triple junctions. The influence of applied stresses on the measured hardness and Young’s modulus was used to assess the residual stresses that were produced in the glass cooling from the processing temperatures. This new technique allows direct evaluation of the effect of the intergranular-phase composition and heat treatment on the mechanical properties of the liquid-phase-sintered alumina ceramics. © 1999 Taylor & Francis Group, LLC.