Abstract
This work investigates the effect of tantalum carbide and vanadium carbide additions on the phase composition, microstructure, and mechanical properties of AlN-based ceramic composites synthesized by mechanochemical solid-state processing followed by thermal treatment. The molar fraction of the carbide additives was varied within the range of x = 0.01-0.10. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy revealed a homogeneous distribution of the reinforcing phases after mechanochemical activation. X-ray diffraction analysis showed that TaC remained chemically stable during processing, leading to the formation of a two-phase AlN-TaC composite with reduced lattice distortions of the AlN matrix. In contrast, VC underwent partial oxidation during heat treatment, resulting in the formation of secondary V 2 O 5 and a different phase evolution. Mechanochemical processing produced a more homogeneous powder morphology and suppressed the formation of large carbide agglomerates, providing favorable conditions for subsequent microstructural development. Mechanical testing demonstrated that a pronounced improvement in hardness and flexural strength occurred at dopant contents above x = 0.03, with the greatest strengthening effect observed for the TaC-containing composites owing to the retention of a stable, uniformly dispersed high-hardness carbide phase. The enhanced mechanical performance is attributed to the combined effects of dispersion strengthening, inhibition of grain growth, grain-boundary strengthening, and crack-deflection mechanisms. These results establish clear relationships between processing, phase evolution, microstructure, and mechanical behavior, demonstrating the potential of mechanochemical processing for the development of high-performance AlN-based ceramic composites intended for demanding structural and hightemperature applications.