Effect of Ceramic Particles on Thermal Stability in Aluminum Matrix Composite: Viewing From Thermal Activation Energy

ABSTRACT This study investigates the influence of ceramic particles on controlling recrystallization and enhancing thermal stability in the pre‐deformed aluminum matrix composite. Using an Al‐Mg alloy reinforced with TiB 2 particles as a model system, we demonstrated that ceramic particles act as potent nucleation sites for recrystallization while pinning grain boundaries to effectively inhibit the growth of recrystallized grains. This synergistic effect results in a significantly refined and thermally stable microstructure in the composite compared to the unreinforced alloy. We proposed a quantitative method to estimate the pinning force of TiB 2 particles and thermal activation energy (Q) for grain growth from microstructure characterization. Our analysis reveals that the pinning force is not static but is influenced by the heat treatment schedule, and the grains recrystallized during low‐temperature annealing exhibit a higher Q value for subsequent growth at elevated temperatures. This enhanced stability is attributed to the large grain boundary curvature resulting from particle‐stimulated nucleation (PSN) at low temperature, which is then effectively stabilized by the TiB 2 particles. These findings provide quantitative insights into the synergistic effects of PSN and Zener pinning, offering guidelines for designing particle‐reinforced metal matrix composites with exceptional microstructural stability for demanding high‐temperature applications.