Formation mechanism of nanocrystalline tungsten–titanium aluminides by ball milling of Ti(C,N)–W powders at subzero temperature

The effects of Al addition and milling at subzero temperatures on the transformation of Ti(C0.5N0.05)–W powder mixtures were investigated using XRD, SEM and TEM. Addition of Al powder improved the kinetics of solid solution between powder constituents. The effect of Al was ascribed to the increase of lattice strain at first stage milling process followed by the fast diffusion of atoms. The refinement of powder particles was not the determinant criteria for solid state dissolution. Multiple ternary compounds could be formed. Aluminium preferably reacted with tungsten. The W(Al,C) and W(Al,Ti) formed were stable, thus solubility of W in Ti(C0.5N0.05) in the presence of Al was limited.