Some indentation and sliding experiments on single crystal and polycrystalline materials

Indentation and sliding experiments were conducted on some fcc, bcc, and hcp structured, single crystal (copper, aluminum, iron, zinc, and cadmium) and polycrystalline (iron, tin, aluminum oxide and magnesium meta-aluminate) materials. Hard indenters (steel, sapphire, and diamond) were used to investigate the anisotropic behavior of these materials in indentation and sliding. A conventional microhardness tester modified to enable sliding of the specimens past the indenter and to incorporate the means for the measurement of frictional force using strain gages was used in this investigation. Optical microscopy (including interference contrast) was used to characterize the specimens after indentation/sliding. An attempt was made to correlate the gross macroscopic behavior in terms of microscopic events. The results of this study show that indentation and sliding on a microscopic scale, such as with a hard indenter can reveal unique characteristics for both single crystal and polycrystalline materials.