Mechanical properties and microstructure of Ti-6.5Al-2Zr-1Mo-1V/TiB composites produced by vacuum arc or selective laser melting

Ti-6.5Al-2Zr-1Mo-1V/TiB metal-matrix composites were produced by vacuum arc or selective laser melting (SLM) methods using 0.7 and 2 wt.% TiB2 in the charge mixture. The initial microstructure of the as-cast and SLM composites consisted of TiB fibers randomly distributed within the two-phase alpha/beta matrix. The average apparent length and cross-sectional size of the TiB fibers in the as-cast composite with 0.7 wt.% TiB2 and as-cast composite with 2 wt.% TiB2 were similar to 10 and similar to 11 mu m and similar to 1.0 and similar to 1.2 mu m, respectively. The average apparent length and cross-sectional size of the TiB fibers in the SLM composite with 0.7 wt.% TiB2 and the SLM composite with 2 wt.% TiB2 were similar to 3.5 and similar to 4.0 mu m and similar to 0.2 and similar to 0.25 mu m, respectively. The addition of the TiB fibers resulted in 20-27% increase in the strength without visible decrease in the ductility. An unreinforced alloy produced by the SLM showed 60% increase in strength compared to that obtained by the vacuum arc melting. The addition of the TiB fibers resulted in similar to 30% increase in the strength (for both composites) with a decrease in the ductility to 8 and 3% for the SLM composite with 0.7 wt.% TiB2 and the SLM composite with 2 wt.% TiB2, respectively.