Design, microstructure and high temperature properties of in-situ Al₃Ti and nano-Al₂O₃ reinforced 2024Al matrix composites from Al-TiO₂ system

This study was conducted to obtain a type of aluminum matrix composites exhibiting a good strength and certain ductility at high temperature. The 25 vol% TiO₂-75 vol%2024 Al systems were selected to fabricate the (Al₃Ti+Al₂O₃)/2024 Al composites with residual ∼32 vol% Al matrix through powder metallurgy. The (Al₃Ti+Al₂O₃)/2024 Al exhibits a good strength and certain ductility at high temperature as in the design. The microstructure of (Al₃Ti+Al₂O₃)/2024 Al composites was investigated. It was discovered that the in-situ Al₃Ti reinforcement was in coarse block-shaped particles of approximately 6.9 μm in size and the Al-Al₃Ti interface was clean. The Al₂O₃ particles were in the nano-scale and distributed in the Al matrix in a cluster form. The high temperature compression testing of the composites was conducted at the temperatures of 573 K, 623 K, 673 K, 723 K and 773 K with the strain rate of 10⁻³ ∼ 0.42 s⁻¹. The results demonstrated that the composites exhibited higher strength at the same high temperature than the other Al matrix composites with a similar volume fraction. The massive Al₃Ti and Al₂O₃ phases played a load bearing role at high temperatures. The residual ∼32 vol% Al matrix led the composites to acquire certain ductility.