ABSTRACT
The same high-density (≈95% of theoretical) coarse grain (≈20 μm) alumina ceramic as discussed in Chapter 17 was utilized for these experiments. To control the extent of damage that such a sharp contact event would create, all of the nanoindentation experiments were conducted at a very low peak load of 106 μN. However, the applied loading rates (103-106 μN⋅s−1) were deliberately varied in these experiments to see whether this led to a change in the material’s response. By varying the loading rates, we are basically affecting the rate of energy transfer from the loading train into the alumina material in question. The effects were explained in terms of shear localization as well as formation of dislocation loops under the Berkovich nanoindenter used on the present alumina samples.
