Hardness and elastic modulus measurements by instrumented nanoindentation

The method of dynamic nanoindentation has been implemented in NanoScan devices. The algorithm is based on measuring and analysis of indentation load-displacement data. This technique underlies the international standard of hardness testing ISO 14577.

The common view of load-displacement diagram. The hardness and elastic modulus calculation parameters are shown on the figure.

The typical experimental graph of load (P) versus depth (h) is shown on Fig. It contains loading and unloading P(h) diagrams. In this method hardness of a sample is calculated as:

where Ас – is indent projection area at maximal indentation load Pmax.

Reduced elastic modulus value is calculated as:

where constant ß depends on indenter geometry, and contact stiffness S is determined by the angle of slope of the tangent to the unloading curve in the point Pmax.

Contact area at maximal load Ас is determined by intenter geometry and contact depth hc and it is described by the tip geometry function Ас = f (hc)

Nanoindentaiton on multiphase materials

Aluminum alloy D16. a) before indentation, b) after indentation