Network formation and mechanical property of additive manufactured TiB/Ti composites

Abstract

TiB was planted into the matrix titanium alloy through the rapid solidification process, and the new ultrafine network reinforced titanium matrix composites (TMCs) powder was formed. Based on the laser additive manufacturing technology, a new titanium matrix composite with alternate distribution of equiaxed network and columnar network structure were creatively fabricated, the formation mechanism of the network structure was systematically discussed, and the mechanical properties of the super-solidified TMCs by additive manufacturing were tested. The results indicate that the network structure (about 9 μm) of the additively manufactured TiB/Ti composites is mainly composed of in-situ nano-TiB whiskers, presenting two crystal structures of B27 and Bf. The direct introduction of B element is easy to form constitutional supercooling at the solidification interface. The equiaxed α phases are obtained by promoting the alternating formation of equiaxed/columnar network structure and refining the grain size. In addition, the formed nano-TiB network structure, not only inhibits the crack deflection and passivate cracks, but also confines the large number of slip lines inside the TiB network structure via in-situ observation, inducing high-density dislocations at the grain boundaries, which limites its plastic deformation, and greatly improves the strength of the composites. The additively manufactured TiB/Ti composites increases the tensile strength by 42%, and maintains the elongation of about 10%.

Keywords

• additive manufacturing
• titanium matrix composites
• network structure
• mechanical property