Additive manufacturing of titanium alloy based composites using directed energy deposition: Study of microstructure, mechanical properties and thermal conductivity

Titanium (Ti) alloys are widely used in aircraft structures, aero-engines, space infrastructure and biomedical applications. However, their low thermal conductivity limits their broader application. In this study, directed energy deposition (DED) was employed for the first to successfully 3D print Ti6Al4V/diamond metal matrix composites (MMCs) with enhanced thermal conductivity and mechanical strength. By careful control of the printing parameters, a high proportion of the diamond (up to 29 wt%) survived the laser melting process. The microstructures, phases, density, hardness, compressive strength, elastic modulus, and thermal properties of the composites were studied. Compared to the directed energy deposited Ti6Al4V alloy, a 200% increase of thermal conductivity at 400 °C was achieved by an incorporation of nominal 40 wt% diamond. Increases in compression strength and modulus were also found in the composites with a nominal diamond loading up to 20 and 30 wt% respectively and the reasons for these variations are explained. These 3D printed metal matrix composites with improved thermal and mechanical properties show a high potential in space applications and as biomedical devices.