graingrowthdominated

Graingrowthdominated is a term used in materials science to describe a regime of microstructural evolution in polycrystalline materials in which grain growth is the dominant mechanism shaping the grain size distribution during thermal treatment. It contrasts with recrystallization-dominated or phase-transformation-dominated regimes.

Mechanism: In this regime, migration of grain boundaries driven by curvature reduces total boundary area and energy, typically following normal or abnormal grain growth, depending on impurities, second-phase particles, and boundary mobility. Recrystallization or nucleation is minimal or absent, so the microstructure evolves primarily through boundary migration and coarsening.

Conditions: It occurs at elevated temperatures and sufficiently long times where stored energy from prior deformation is low or when pinning is weak; it can be altered by precipitates or inclusions that either pin boundaries (Zener pinning) or promote abnormal growth.

Kinetics and observations: The average grain size often follows a parabolic growth law with time, d^2 ≈ d0^2 + k t, though abnormal growth yields a broad distribution with a few very large grains. Microstructural indicators include increasing mean grain size, reduction in boundary area, and possible texture development.

Implications: Controlling graingrowthdominated regimes is important for properties such as strength, toughness, and conductivity. Processing strategies include adding pinning particles, optimizing temperature and time, or engineering the initial microstructure to limit coarsening.

Related concepts: grain growth, recrystallization, abnormal grain growth, Zener pinning.