Nanostructural peculiarities affecting strength and crack growth resistance of a Ti-Si-X composite at room and high temperatures up to 800 °C

• Nanostructural peculiarities affecting flexural strength and fracture toughness of the studied Ti-Si-X composite in a temperature range of 20 °C to 800 °C were explored. • The main factors that affected the integrity of the Ti-Si-X composite were explored, namely, multiple microcracking of titanium carbide phase microareas, rapid fracture of thin membranes between nanopores in the titanium carbide phase, coalescence of nanopores by creep mechanism at high temperatures, and fracture of the ceramic particles themselves. • The upper operating temperature limit of 700 °C was determined for the Ti-Si-X composite as a trade-off between its flexural strength and fracture toughness. High-temperature Ti-based composites belong to a new class of materials possessing chemical inertness, high strength and fracture toughness, moderate ductility, and high-temperature corrosion resistance. Since these composites exhibit a set of specific physical and chemical properties under harsh conditions, they are applied for fabricating critical parts of high-temperature structures and chemical equipment. In this work, a simple method of producing a novel Ti-based composite (Ti-Si-Al-Zr-C system) by arc melting an α-Ti alloy blank, Zr pellets, SiC powder, and Ti 3 SiC 2 MAX phase powder has been developed. Phase and microstructure analyses of the studied Ti-Si-X composite were performed, and its flexural strength and fracture toughness were estimated at room and high temperatures in a range of 400 °C to 800 °C, with the determination of dominant fracture micromechanisms. High levels of flexural strength and fracture toughness, exhibiting an advantage over known commercial high-temperature Ti-based alloys and Ti-based composites, were achieved in the Ti-Si-X composite at both room and high temperatures up to 700 °C. The ways of further increasing these parameters and limitations in operating temperature of the composite were substantiated based on the main nanostructural factors that affect the integrity of the composite.