Designing multi-scale architecture for simultaneously improved strength and ductility in titanium matrix composite

Additive manufacturing (AM) offers significant potential to create ingenious multi-scale architecture with superior properties, here, for the enhanced strength coupled with a prolonged elongation, titanium matrix composites (TMCs) with multi-scale TiB distribution architecture were designed and fabricated via AM through tailoring the B (boron) element concentration nonuniformity at micrometer-scale. The microstructural examination showed that B-lean regions were surrounded by B-rich ones, and the bimodal grain size structure of prior β-Ti grains was found. In the B-lean regions, plate-like TiB phase distributed homogenously, while a network distribution of whisker-like TiB was observed in the B-rich regions. The improved strength (967 MPa → 1131 MPa, improved by 16.9 %) coupled with prolonged elongation (9.8 % → 11.5 %, improved by 17.3 %) could be attributed to the stress bearing from whiskers and hetero-deformation-induced strengthening effect. Meanwhile, the relatively large size of B-lean regions contributed as a ductile phase, promoting crack deflection/bluntness.