Synthesis, Microstructure, and Mechanical Properties of a Novel Ti₂AlC/TiC/Al₂O₃In Situ Composite

Abstract

This paper describes a novel process for synthesizing a Ti₂AlC/TiC/Al₂O₃in 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 μm) 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.