Microstructure and mechanical properties of a Mo-toughened Mo3Si-based in situ nanocomposite

•The mechanical parameters of Mo3Si were obtained from first-principles calculations.•Based on the calculated results, MoSi2 is significantly more brittle than Mo3Si.•A Mo-toughened Mo3Si-based coating was synthesized onto a Ti–6Al–4V substrate.•Both damage resistance and hardness of a Mo3Si coating are improved by Mo addition.

To explore the plasticity of cubic A15-structured Mo3Si, mechanical parameters, including bulk modulus, shear modulus, Young's modulus, Cauchy's pressure and Poisson's ratio are obtained from first-principles calculations. Subsequently, a Mo-toughened Mo3Si-based nanocomposite coating is synthesized in-situ onto a Ti–6Al–4V substrate by a double glow discharge plasma technique. The new coating exhibits a dual-phase microstructure, where a coarser-grained Mo-rich phase is uniformly distributed within a finer-grained Mo3Si matrix. The results show that the incorporation of the “coarser-grained” Mo phase improves both damage resistance and hardness of the monolithic Mo3Si nanocrystalline coating.