Comparison of different analysis methods in nanoindentation and influence on the correction factor for contact area

The classical area function technique used for nanoindentation measurements is compared to the two-slope method, a recent method rarely used which is based on the calculation, at maximum load, of the slopes of the loading and unloading curves. Both methods are used with two different ways of calculating the unloading contact stiffness and their effects on the elastic modulus and hardness measurements are compared. The influence of these different ways of calculating on the correction factor for contact area that is present in the fundamental relationship between contact stiffness, Youngʹs modulus and contact area is also analysed and discussed. It is confirmed on three different materials, fused quartz, titanium and magnesium oxide, that this correction factor is not only depending on the indenter geometry but also on the tested material.