Simultaneously Improve the Strength and Ductility of the As-Sintered Ti Composites by Pre-Planting Ultra-Fine Network into the Composites Powder

Abstract

This study proposed a novel technique to effectively solve the microstructure deterioration problem of the as-sintered titanium matrix composites (TMCs) by pre-planting TiB nano-fibers and La₂O₃ nano-particles as ultra-fine network distribution into initial powder. The novel ultra-fine network exerted significantly fine-grain effect, which effectively optimized the coarse Widmannstatten (33.5μm) to fine-equiaxed grains (8.4μm) and simultaneously improved their strength and ductility. The as-sintered (TiB+La₂O₃)/IMI834 composites exhibited highly promising combination of excellent tensile strength, ductility and high temperature strength. 1.2 vol%-TMCs largely improved the elongation from 2.18% to 10.81% without reducing its yield strength, while the tensile strength of 2.4 vol%-TMCs reached 780.5 MPa at 600℃ which was superior than many as-forged TMCs. Its strengthening and toughening effects mainly attributed to the fine-grain effects and the synergistic effect between nano-reinforcements and soft matrix. This work opened up a new route for directly sintering of low-cost TMCs in high comprehensive properties.

Keywords: Titanium matrix composites, Hot pressed sintering, Grain refinement, Microstructure, Mechanical property