On microstructure and room-/high-temperature properties of an Al2O3/Al-Cu-Mn composite

• The Al2O3/Al-Cu-Mn composite exhibits a 41% increase in yield strength at room temperature (from 187 MPa to 263 MPa) compared to the base alloy after T6 treatment. • At elevated temperatures, the composite maintains enhanced yield strength, achieving 52 MPa at 400 °C, indicating superior high-temperature performance. • In-situ synthesized nano-sized γ-Al2O3 particles, predominantly distributed along grain boundaries, are identified as the primary strengthening mechanism, especially at high temperatures. • This work provides a reference for designing high-performance aluminum matrix composites for high-temperature applications, leveraging in-situ reinforcement strategies.