rekristallisaatioon

Rekristallisaatioon is a Finnish term referring to recrystallization, a process primarily used in materials science and chemistry to purify solid compounds or to modify the microstructure of metals and alloys. In chemistry, it is a technique used to purify solid organic compounds. The impure solid is dissolved in a minimal amount of hot solvent in which the desired compound is soluble at high temperatures but less soluble at low temperatures, while impurities are either insoluble or highly soluble in the solvent. Upon cooling, the pure compound crystallizes out, leaving the impurities behind in the solution. The choice of solvent is crucial for effective recrystallization.

In metallurgy, recrystallization is a process that occurs in a metal or alloy during heating above a specific temperature, known as the recrystallization temperature. This process involves the formation of new, strain-free grains within the deformed material. When a metal is cold-worked, its grains become elongated and distorted, increasing its hardness and strength. Upon heating to the recrystallization temperature, atomic diffusion and grain boundary migration lead to the nucleation and growth of new, equiaxed (equidimensional) grains. This results in a softening of the material and a reduction in its strength and hardness, often restoring its ductility. The recrystallization temperature varies depending on the metal or alloy and the degree of prior cold work.