セラミック基ナノ複合材料における残留応力と擬強化

抄録

Residual stresses in Al₂O₃ and Si₃N₄-matrix nanocomposites (added with β-SiC or WC phase) have been measured by piezo-spectroscopy. The highest residual stress value was found in Al₂O₃-matrix materials. Machining procedures have been found to play a minor role in the formation of residual stresses. Analyses of both spectroscopic and strength data suggest that, when the coefficient of thermal expansion of the matrix material is much higher than that of the added dispersoid, an apparent strengthening effect may arise in nanocomposite materials. However, this effect does not arise from an actual enhancement of the inherent material toughness, since it is proved that any strength enhancement vanishes in presence of externally introduced flaws≥30μm.