Insights into hydrogen-induced strengthening mechanism of TiC/Ti6Al4V via experiments and first-principles calculations

This study is dedicated to summarize the strengthening mechanism of hydrogen microalloying for titanium matrix composites, i.e., 5 vol% TiC/Ti–6Al–4V, which is manufactured employing a unique technique called “melt hydrogenation” that involves melting alloys under a gas mixture of hydrogen and argon. This process enables the direct integration of trace hydrogen atoms into composites. The experimental results demonstrate that melt hydrogenation not only refines the microstructure of matrix but also promotes the network-like distribution of reinforcements. The three-dimensional atom probe tomography analysis of TMCs shows that the TiC/matrix interfaces can effectively trap hydrogen. Combining the high-resolution transmission microscopy observation and ab-initio calculation on the interface between matrix and reinforcement, it suggests that the addition of hydrogen improves the interfacial adhesion work, which has important implications for the improvement of load-bearing capacity of interface. Therefore, thanks to the above-mentioned structural changes, the room-temperature strength and plasticity can be simultaneously improved with the minor addition of hydrogen. These findings are of great significance for the further development of high-performance titanium matrix composites.