Synthesis, microstructure, and mechanical properties of a novel Ti2AlC/TiC/Al2O3 in situ composite

This paper describes a novel process for synthesizing a Ti2AlC/TiC/Al2O3 in situ composite. This route utilizes TiO2, carbon, and Al powders as raw materials, and involves high-energy mechanical milling and powder sintering. The Ti2AlC/TiC/Al2O3 bulk in situ composite produced has a phase composition of Ti2AlC-20 vol% TiC-35 vol% Al2O3 with fine Al2O3 particles (size: 0.5-15 mu m) embedded in a Ti2AlC/TiC matrix. The Ti2AlC grains exhibit a nanometer scale lamellar structure, and most of the Al2O3 grains contain fine cubic TiOmC1-m precipitates (size: 10-200 nm). The average hardness and bending strength of the composite are in the ranges of 11-12.5 GPa and 380-440 MPa, respectively. Here we have demonstrated that the mechanical performance (mainly hardness and bending strength) of the composite is directly correlated with the size of the Al2O3 particles present in the as-fabricated in situ composite.