Investigation of network microstructure of TiB/Ti6Al4V-ELI composite manufactured with laser metal deposition

Abstract

This work presents the microstructural investigation of an in situ synthesized TiB/Ti6Al4V-ELI composite that was manufactured with additive manufacturing (AM) technique known as laser metal deposition (LMD). A single-track sample was manufactured by adding TiB2 to Ti6Al4V-ELI at mass deposition volume of 5% and characterized for microstructure and hardness. It was found that in situ reaction promoted the formation of quasi-continuous network microstructure of TiB whiskers with a needle-like morphology, in a martensitic a' matrix. Furthermore, the manufactured TiB/Ti6Al4V-ELI presented two different grain growth morphologies, with smaller and large TiB network grains observed at the top and bottom of the sample, respectively, due to heat travelling direction. A high hardness of 513 HV was observed at the top of the sample, which was reduced to 483 HV at the bottom, promoted by grain growth.