Vacancy

A type of structural imperfection in which an individual atom site is temporarily unoccupied.

Vickers Hardness (Test)

Standard method for measuring the hardness of metals, particularly those with extremely hard surfaces; the surface is subjected to a standard pressure for a standard length of time by means of a pyramid shaped diamond. The diagonal of the resulting indention is measured under a microscope and the Vickers Hardness value read from a conversion table.