Tvrdosti

Tvrdosti, or hardness, is a material property that describes resistance to permanent deformation, indentation, or scratching. It is context-dependent, and several tests and scales exist for different materials and phenomena.

In minerals and geology, Mohs hardness is the traditional scale, ranking minerals from 1 (talc) to 10 (diamond) by scratch resistance. For engineering materials, indentation-based tests—such as Rockwell, Vickers, and Brinell—measure the resistance to penetration under a defined load. The Vickers test uses a diamond pyramid, while Rockwell relies on various indenters and scales to capture different loads and depths.

Hardness is influenced by composition, crystal structure, grain size, phase distribution, and heat treatment. In metals, processes like alloying and heat treatment can increase hardness through precipitation strengthening or work hardening, but often at the expense of toughness. In ceramics and composites, high hardness is common and desirable for wear resistance. There is not a direct universal relationship between hardness and strength or toughness; materials can be hard but brittle.

Practically, hardness informs material selection for tools, wear components, coatings, and machining. In geology, hardness helps identify minerals and understand their weathering and formation conditions.

The term tvrdosti derives from Slavic roots meaning hard. In scientific usage, it encompasses several related concepts and measurement approaches, each appropriate to different materials and applications.