Vickers hardness index
The Vickers index measures the hardness of a material using a hardness test.
Hardness is the ability of a material to oppose the penetration of a hard body, which is why the hardness test consists in making an imprint on the sample using a penetrator subjected to a known force.
The test consists in applying a force F (in newtons) to a square-based diamond pyramid with a 136° vertex. The pressure must be maintained for 15 s before measuring the diagonal of the square form of the imprint produced in the material by the pyramid. A formula is then used to give the value of the Vickers hardness index.