In 1992, Warren Oliver and George Pharr published an article that revolutionized hardness testing. The genius of Oliver and Pharr was that they devised a way to know the size of a hardness indentation without imaging it. This development disrupted Vickers and Knoop microhardness testing, which required direct measurement of the lengths of the indentation diagonals. Not having to image the indentation paved the way for fully automated hardness testing. Not only was automated testing independent of human bias, it was also much faster, because multiple tests on multiple samples could be prescribed and executed with no human intervention. Further, the Oliver-Pharr method extended hardness testing to much smaller scales, because one could determine the size of even sub-micron indentations with high accuracy. This session introduces the theory of the Oliver-Pharr method and shows how it can be used to obtain an equivalent Vickers hardness number (HVc).

See the KLA nanoindenters by visiting https://www.kla.com/products/instruments/nanoindenters.