Titanium alloyed with rhenium by selective laser melting

The paper presents results of processing Ti-Re alloys by consolidating mixtures of powders of both metals with the use of selective laser melting (SLM). Ti-based alloys containing 0.5, 1.0 and 1.5 at% Re were obtained in this way. Optimum process parameters were determined by accepting the criterion of minimum porosity of manufactured parts and maximum effectiveness of dissolving Re particles in molten Ti. Density of the SLM-processed parts reached over 99.9% and 90-85% of Re powder (by volume) was dissolved. The effects of Re content on the microstructure and mechanical properties of SLM-processed parts in as-built condition were investigated. Light microscopy and X-ray diffraction examinations revealed that rhenium changed the microstructure of CP-Ti lath-type α′ martensite to acicular-shaped by lowering the temperature of martensitic transformation. A very intensive effect of strengthening titanium by the addition of small amounts of Re was found, due to α′-lattice distortion and grain refinement. Alloying with 1.5 at% Re made it possible to obtain mechanical properties similar to those of the SLM-processed Ti6Al4V alloy in as-built condition.