Berkovich tip

A Berkovich tip, with "a" denoting the half angle

A scanning electron microscope image of a Berkovich tip used in a nanoindenter

A Berkovich tip is a type of nanoindenter tip used for testing the indentation hardness of a material. It is a three-sided pyramid which is geometrically self-similar. The popular Berkovich now has a very flat profile, with a total included angle of 142.3° and a half angle of 65.27°, measured from the axis to one of the pyramid flats. This Berkovich tip has the same projected area-to-depth ratio as a Vickers indenter. The original tip shape was invented by Russian scientist E. S. Berkovich in the USSR around 1950, which has a half angle of 65.03°.[1][2]

As it is three-sided, it is easier to grind these tips to a sharp point and so is more readily employed for nanoindentation tests. It is typically used to measure bulk materials and films greater than 100 nanometres (3.9×10^−6 in) thick.

References

1. E. S. Berkovich, "Three-Faceted Diamond Pyramid for Micro-hardness Testing", Zavodskaya Laboratoria, Vol. 16, #3, 1950, p. 345–347 (in Russian). Translated into English and published in Industrial Diamond Review, Vol. 11, No. 127, June 1951, p. 129–132.
2. M. M. Khrushchov & E. S. Berkovich, "Methods of Determining the Hardness of Very Hard Materials: The Hardness of Diamond", Zavodskaya Laboratoria, 1950 (2), p. 193–196 (in Russian). Translated into English by W. G. C. and published in Industrial Diamond Review, Vol. 11, Feb 1951, p. 42–49 (in English).