Detection of residual stresses in glass-penetrated polycrystalline aluminawith 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 regio ns of the sample to measure both the hardness and Young's modulus of the gl ass contained at interfaces and in triple junctions. The influence of appli ed 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 pro cessing temperatures. This new technique allows direct evaluation of the ef fect of the intergranular-phase composition and heat treatment on the mecha nical properties of the liquid-phase-sintered alumina ceramics.