Enhanced strength-ductility synergy in laser additive manufactured TC4 titanium alloy by grain refinement

In this study, a significant refinement of prior-beta grains was achieved in the TC4 (Ti-6Al-4V) titanium alloy through the addition of zirconium diboride (ZrB2), made additively by laser melting deposition (LMD). With the increase of ZrB2 content, the fine basket-weave structure was obtained instead of alpha-Widmansta spexpressioncing diexpressioneresis tten laths. The tensile results shown that the mechanical anisotropy of modified-TC4 alloys was decreasing in comparison with the as-deposited TC4 alloy. The higher content of forming eutectoid TiB phase resulted in the higher strength by precipitation strengthening but poorer elongation in the vertical direction. TC4 + 0.5ZrB(2) (TC4 with 0.5 wt% ZrB2 addition) alloy exhibited the excellent combination of strength and ductility and presented isotropic characteristics, which could be related to the synergetic effect of refinement of prior-beta grains and alpha phase and the trace formation of TiB phase.