What shape impression does the Vickers test produce?

The Vickers test is a method used to measure the hardness of materials by applying a specific load on a diamond-shaped indenter. When the indenter is pressed into the material's surface, it creates an impression characterized by a square shape. This square impression is formed due to the geometric nature of the diamond indenter, whose point is designed to produce a precise and measurable mark on the material.

The square shape allows for two diagonals to be measured, and the average of these diagonal lengths is used to calculate the Vickers hardness number (HV). This measurement is crucial as it provides a standard way to discuss and compare the hardness of different materials. Other shapes such as circular, triangular, or hexagonal impressions do not reflect the specific manner in which the Vickers test operates, as the diamond indenter's geometry is specifically designed to create a square impression under load.