A Novel Al–Cu Composite with Ultra-High Strength at 350 °C via Dual-Phase Particle Reinforced Submicron-Structure

Thermal stability determines a material's ability to maintain its performance at desired service temperatures. This is especially important for aluminum (Al) alloys, which are widely used in the commercial sector. Herein, an ultra-strong and heat-resistant Al-Cu composite is fabricated with a structure of nano-AlN and submicron-Al₂O₃ particles uniformly distributed in the matrix. At 350 °C, the (8.2AlN+1Al₂O₃)_p/Al-0.9Cu composite achieves a high strength of 187 MPa along with a 4.6% ductility under tension. The high strength and good ductility benefit from strong pinning effect on dislocation motion and grain boundary sliding by uniform dispersion of nano-AlN particles, in conjunction with the precipitation of Guinier–Preston (GP) zones, enhancing strain hardening capacity during plastic deformation. This work can expand the selection of Al–Cu composites for potential applications at service temperatures as high as ≈350 °C.