Activating Trace Fe Impurity as Catalyst to Plant Carbon Nanotubes Within Ti-6Al-4V Powders for High-Performance Ti Metal Matrix Composites

External catalysts are commonly pre-coated on Ti alloy powders for in situ synthesis of carbon nanotubes (CNTs) to resolve the inhomogeneity issue, but their excessive introduction changes the matrix composition. Here, we activated the catalytic function of trace Fe impurity solid solute in Ti-6Al-4V powders to plant CNTs within the Ti-6Al-4V powders without modifying the composition. These CNTs exhibited high reactivity with Ti, were retained in the consolidated composites, and improved the mechanical properties.