Investigation on the elevated-temperature tribological behaviors and mechanism of Al-Cu-Mg composites reinforced by in-situ size-tunable TiB2-TiC particles

Lightweight materials design of friction parts promises aluminum matrix composites to achieve comparable anti-wear properties as steel. However, it is still challenging due to the limited effects of monotonous reinforcement. In this work, (TiB2-TiC)/Al-Cu-Mg composites were fabricated with particle content from 10 to 60 vol% and scaled from nano-sized to nano-/micron-sized. The microstructures, mechanical properties, elevated-temperature tribology behaviors and wear mechanisms of the Al-Cu-Mg composites reinforced by TiB2-TiC particles with tunable size and volume fractions were systematically investigated. Compared to the Al-Cu-Mg composite reinforced by nano-sized particles, the significant micron-/nano-sized effect and thicker mechanical mixture layer in the composites can weaken the influence of load on the composites and thus better protect the matrix. The incorporated particles evolved from single nano-sized to micron-/nano-sized hybridized, and the dominant wear mechanism transformed from severe adhesive and delamination wear (surface fatigue) to slight adhesive wear. 60 vol% micron-/nano-sized (TiB2-TiC)/Al-Cu-Mg composite showed the lowest wear rate (0.047 mm3/m) and coefficient of friction (0.38) at 473 K, 0.32 mm/s sliding velocity and 40 N load, reduced 24% and 20% than composite with 10 vol% nano-sized particles. This work provided a strategy for improving the wear resistance of aluminum matrix composites reinforced by size-tunable particles for their extended applications on structural components.