Microstructure and Mechanical Properties of L12-(Al, Cr)3Ti/TiB2+Ti2AlC Composites Produced by Reactive Arc-Melting

The L12-(Al, Cr)3Ti/TiB2+Ti2AlC composites were prepared by reactive arc-melting from the elemental powders of titanium, aluminum, chromium, and B4C powder. The resulting composites have reinforcement 3.8, 7.5, and 15 vol% (TiB2+Ti2AlC) in the matrix of L12 trialuminide Ti–61Al–14Cr alloy. The TiB2 particles were mass-like with 5–10 μm in diameter, while the Ti2AlC particles were rod-like in shape with 1–2 μm in width and 5–15 μm in length and they are homogeneously distributed in the matrix. These composite materials have a high strength at ambient temperature; about 600 MPa with an ambient temperature ductility of 0.3–0.4% (plastic bend strain). The fracture toughness tests have shown that the composites have higher toughness than that of the matrix alloy. The zigzag cracks propagated in the composite, and the reinforcements TiB2 and Ti2AlC particles and the fine grains of matrix were the main obstacles to the crack propagation.