Lösningshärdhet

Lösningshärdhet, also known as solution hardening or solid-solution strengthening, is a strengthening mechanism in metallurgy. It is achieved by adding one or more alloying elements to a base metal, forming a solid solution. In this state, the atoms of the alloying element are dispersed uniformly within the crystal lattice of the base metal.

The strengthening effect arises from the lattice distortion caused by the solute atoms. These solute atoms, whether they are larger or smaller than the solvent atoms, create local stress fields within the lattice. These stress fields impede the movement of dislocations, which are line defects in the crystal structure responsible for plastic deformation. When dislocations encounter these stress fields, their ability to move and propagate is hindered, requiring a higher applied stress to cause deformation.

The degree of strengthening depends on several factors, including the concentration of the solute element, the difference in atomic size between the solute and solvent atoms, and the chemical interaction between them. Generally, higher concentrations and greater atomic size mismatches lead to more significant strengthening. Common examples of lösningshärdhet are found in alloys like brass (copper and zinc) and stainless steel (iron, chromium, and nickel). This technique is widely used to improve the mechanical properties, such as yield strength and hardness, of metals for various applications.