Interaction of a Ti–Cu Alloy with Carbon: Synthesis of Composites and Model Experiments
Titanium carbide (TiC), is the most thermodynamically stable compound in the Ti–C–Cu system, which makes it a suitable reinforcement phase for copper matrix composites. In this work, the interaction of a Ti–Cu alloy with different forms of carbon was investigated to trace the structural evolution leading to the formation of in-situ TiC–Cu composite structures. The reaction mixtures were prepared from Ti25Cu75 alloy ribbons and carbon black or nanodiamonds to test the possibilities of obtaining fine particles of TiC using ball milling and Spark Plasma Sintering (SPS). It was found that the behavior of the reaction mixtures during ball milling depends on the nature of the carbon source. Model experiments were conducted to observe the outcomes of the diffusion processes at the alloy/carbon interface. It was found that titanium atoms diffuse to the alloy/graphite interface and react with carbon forming a titanium carbide layer, but carbon does not diffuse into the alloy. The diffusion experiments as well as the synthesis by ball milling and SPS indicated that the distribution of TiC particles in the composite structures obtained via reactive solid-state processing of Ti25Cu75+C follows the distribution of carbon particles in the reaction mixtures. This justifies the use of carbon sources that have fine particles to prepare the reaction mixtures as well as efficient dispersion of the carbon component in the alloy–carbon mixture when the goal is to synthesize fine particles of TiC in the copper matrix.