Heat treatment that develops a fine dispersion of a new solid phase in an alloy, impeding dislocation motion. It is distinct from precipitation from a liquid chemical solution. A solid solution may first be formed at high temperature, quenched to retain supersaturation, and then aged to promote solid-state precipitation.
For one spherical particle per representative volume , a volume fraction implies . A mean nearest-neighbor distance in a random population does not determine this number density exactly, and an atomic thermodynamic phase fraction requires a molar-volume conversion before it is used as .
A dislocation unable to shear an obstacle can bow around it and leave a loop. Balancing the Peach-Koehler force against the tension of a curved dislocation gives the critical scale , where is the free obstacle span on the slip plane. Centre pitch and free span are not interchangeable when particle size is appreciable.
An obstacle calculation produces a resolved shear-stress increment. A single crystal needs its Schmid factor, while a polycrystal needs a deformation-geometry or Taylor factor. The relation therefore requires an explicit orientation assumption rather than a universal tensile prefactor.
Resistance to dislocation motion caused by the energetic cost of disrupting chemical order, for example creating an antiphase boundary in a gamma prime phase precipitate.
A new solid phase formed within an existing solid matrix. Its morphology reflects anisotropic interfacial energy, coherency strain and growth kinetics.
Evolution toward larger characteristic precipitate sizes, often by diffusional growth of larger particles at the expense of smaller ones. The associated changes of spacing and shape can alter strengthening.
The shape of a solid-state precipitate. Thin plates can result when broad faces have much lower interfacial energy than edge regions.
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Precipitation hardening, also known as age hardening, is a heat treatment process used to increase the strength and hardness of certain metal alloys, particularly those that are non-ferrous, such as aluminum, titanium, and nickel-based alloys. The process involves the formation of fine particles or precipitates within the metal matrix, which impede the movement of dislocations and enhance the material's mechanical properties.