Effect of reinforcements on β→α transformation and tensile properties of a near α titanium matrix composite

In this paper, the (TiB + TiC + Y₂O₃)/α-Ti composite were fabricated by vacuum arc melting furnace to investigate microstructure evolution and tensile properties. With reinforced with ternary reinforcement (TiB + TiC + Y₂O₃), α_GB is almost disappeared at the prior β grain boundary and β grain size decreases by an order of magnitude. The distribution of reinforcement is homogeneous and mainly distributed at β grain boundary and α colony boundary. In general, in matrix, α_GB is preferred to simultaneously maintain Burgers orientation relationship with two adjacent β grains. However, in (TiB + TiC + Y₂O₃)/α-Ti composite, α_s direct precipitates in β grain and grows in more equiaxed-like without forming α_GB at grain boundary because of the constitutional undercooling and heterogeneous nucleation caused by (TiB + TiC + Y₂O₃), thus promotes the formation of non-Burgers related α grain which weaken α texture at last. In addition, the composite shows incredible performance at 973 K that achieved both high strength and ductility. The strengthening mechanism has also been discussed informally.