Which of the following hardness testers will be used because it has a small indentation size suitable for thinner samples?

The Vickers hardness tester is particularly suitable for measuring the hardness of thinner samples due to its use of a diamond pyramid indenter, which creates a small indentation size. This characteristic allows for the analysis of smaller areas and harder materials, making it ideal for applications where precision is necessary, such as in the evaluation of thin films or coatings.

In contrast, the Brinell hardness test, which utilizes a hardened steel or carbide ball, creates a much larger indentation and is therefore better suited for thicker materials. The Rockwell hardness test can also vary in indentation size depending on the scale used, but generally, it does not achieve the same level of precision for thin samples as the Vickers test. The Knoop hardness test also employs a diamond indenter, and while it produces a small impression, its primary use is focused on very brittle materials or thin layers, which means the Vickers method is often preferred for its versatility and ability to provide reliable results on a wider range of materials. Thus, for applications involving thinner samples, the Vickers hardness test is the method of choice.