Mutual consistency of hardness testing at micro- and nanometer scales

Abstract To a considerable degree hardness is an empirical value which depends on many details involved in the measuring process. In the present work, hardness values were measured in the depth range 2 – 800 nm using microhardness, nanoindentation and scratch hardness tests on fused silica, steel and sapphire. It is shown that overestimation of hardness values for steel and sapphire with the nanoindentation method can be directly related to the relative height of pile-ups observed on the topography image of the indentation imprint. It is also shown that the scratch hardness test is a promising technique for nanoscaled hardness measurements.