Simultaneously improving the strength and ductility of the as-sintered (TiB+La2O3)/Ti composites by in-situ planting ultra-fine networks into the composite powder

Abstract

This study creatively proposed a technique to effectively overcome the strength-ductility mismatch of the as-sintered titanium matrix composites by in-situ planting TiB nano-fibers and La2O3 nano-particles as ultra-fine networks into the composite powder. (TiB+La2O3)/Ti composites with excellent strength-ductility synergy were fabricated by hot pressing. The ultra-fine network eliminated the Widmanstatten microstructure and exerted a significantly fine-grain effect. Thus, the elongation of the as-sintered 1.2 vol.% (TiB+La2O3)/Ti composite was significantly improved from 2.2 to 10.8% compared with the matrix alloy, and the ultimate tensile strength was simultaneously enhanced to 1098.6 MPa. Meanwhile, the tensile strength of 2.4 vol.% (TiB+La2O3)/Ti reached 774.8 MPa at 600 °C, even superior to many wrought composites. The strength-ductility synergy effects were mainly attributed to the significant fine-grain effect and the synergistic effect between nano-reinforcements and soft matrix. This work opened up a new route for directly sintering nanoparticles reinforced titanium matrix composites components with promising comprehensive properties.