OS05W0295 Deformatio behaviou of ceramics under repeating nanoindentation

抄録

The deformation behaviour of metal: Ti (as reference material), glass: Pyrex and soda-lime, and ceramics: ZrO_2 and Al_2O_3 have been studied under repeating nanoindentation with fixed maximum and minimum loads and 5 mN/s loading speed for 10 cycles. Three characteristics of deformation behaviour i.e. forward/backward deviation and hysteresis loop of load-displacement curves and pile-up of the material around the indent mark are compared to each other. In titanium, forward deviation, looping and pile-up were observed. In Pyrex glass, forward deviation without looping and no ^piling-up were observed. In soda-lime glass, backward deviation, comparatively big loops and pile-up were observed at higher loads. The existence of residual stress is the primary reason for backward deviation. The reason for the looping is the difference in the stored and released strain energy which corresponds to the random distorted movement of the amorphous structured glass molecules. Backward deviation was observed in as-supplied zirconia but forward deviation in polished zirconia. In both the cases no looping occurred but pile-up appeared. In alumina, forward deviation without looping and pile-up were observed. Thus deformation behaviour under repeating nanoindentation is strongly affected by material structure and surface condition.