Berkovichindenter

The Berkovich indenter is a three-sided pyramidal diamond tip used in instrumented indentation, commonly referred to as nanoindentation, to assess the mechanical properties of materials at small scales. Its geometry yields a well-defined projected contact area that increases with indentation depth, enabling calculation of properties such as hardness and elastic modulus from load-displacement data.

Designed as a sharp, durably manufactured tip, the Berkovich indenter is mounted on a nanoindenter or hardness tester and interacts with the sample surface as a rigid or nearly-rigid geometry. The precise area–depth relationship is described by an area function A(h), which is determined through calibration and accounts for tip rounding and wear. Because the tip can wear over time, regular verification against reference materials is standard practice to maintain measurement accuracy.

In a typical test cycle, a load is applied to a maximum value, held, and then released while recording the load and displacement. From the resulting P–h curve, hardness H is obtained as the maximum load divided by the contact area at maximum depth, H = Pmax/A(hc). The sample’s elastic modulus is derived from the unloading stiffness using the Oliver–Pharr method, incorporating the indenter geometry and a Poisson’s ratio estimate for the material.

Applications span metals, ceramics, polymers, thin films, and coatings, where small-volume samples or surface phenomena are of interest. Limitations include tip wear, surface roughness, creep effects, and calibration sensitivity. Proper maintenance, calibration against standards, and awareness of material response are essential for reliable measurements with a Berkovich indenter.