Strength-ductility synergy of in-situ TiB/Ti6Al4V composites with tailored hierarchical TiB distributions

In-situ TiB whiskers reinforced Ti6Al4V (TC4) composites with hierarchical reinforcement distributions have been ingeniously designed and fabricated. The structure was characterized by a network distribution of the in-situ generated TiB whiskers in the TC4 matrix together with a homogeneous distribution of TiB whiskers inside the network cells. The designed composites possessed a remarkable strength-ductility synergy with the simultaneous improvement of tensile strength and elongation by 21% and 80%, respectively, compared with the matrix TC4 alloy. An in-situ tensile test was performed, and the microstructure evolution proved that the network distributed TiB afforded the excellent ductility. The homogeneously distributed TiB inside the network cell improved the strengthening efficiency and did not hinder the slip of the TC4 matrix. This study opened up a new way to circumvent the strength-ductility tradeoff of titanium matrix composites.