TiAl/Ti2AlC composites were successfully synthesized by vacuum arc melting with TiC, graphite powder, and carbon nanotubes (CNTs) as carbon sources. As the amount of Ti2AlC ceramic increased, the microhardness and compressive strength of the TiAl/Ti2AlC composites improved linearly. Importantly, the TiAl/Ti2AlC prepared with TiC as the carbon source exhibited higher microhardness and compressive strength than that composites prepared with graphite powder or CNTs. During vacuum arc melting, three reactions occur successively: Ti+Al→TiAl, Ti+C→TiC, and TiAl+TiC→Ti2AlC. Ti2AlC was formed by peritectic reaction between the TiAl melt and TiC particles. A large amount of TiC was left in the TiAl matrix, which acted to improve the hardness and strength of the composites. The fracture behavior of the composite was mainly transgranular fracture. The pinning, pulling out, and the effect of crack deflecting of TiC particles, together with the interlayer tearing, plastic shearing, folding, and crimping of Ti2AlC played a key role in the improvement of the strength and plasticity of the composites.

Effect of carbon reactant on microstructures and mechanical properties of TiAl/Ti2AlC composites

Layered ternary MAX phases and their MX particulate derivative reinforced metal matrix composite:A review

Lamellar structure and effect of Ti2AlC on properties of prepared in-situ TiAl matrix composites

Formation of TiC/Ti2AlC and α2+γ in in-situ TiAl composites with different solidification paths

Microstructural and mechanical properties of dual Ti3AlC2–Ti2AlC reinforced TiAl composites fabricated by reaction hot pressing

The phase transitions in the Ti–Al and the Ti–Al–C systems are investigated by the differential thermal analysis (DTA) and X-ray diffraction (XRD). The results reveal that the addition of C not only leads to the formation of the Ti 2 AlC phase but also lowers the formation temperatures of the TiAl and Ti 3 Al phases. In the both systems, the combustion synthesis reactions are ignited at the melting point of Al, so the TiAl alloy and the Ti 2 AlC/TiAl composites are successfully fabricated at a lower temperature (about 660 °C) with an applied pressure. The yield strength, the ultimate compression strength and the work hardening rate of the Ti 2 AlC/TiAl composites are all higher than those of the TiAl alloy and increase with the increase in the Ti 2 AlC content. The average ultimate compression strength of the 6 vol.% Ti 2 AlC/TiAl composite is 179 MPa higher than that of the TiAl alloy without sacrificing ductility.

Sijie Lü

Papers

Phase transitions and compression properties of Ti2AlC/TiAl composites fabricated by combustion synthesis reaction