Effects of trace reinforcements on microstructure and tensile properties of in-situ synthesized TC18 Ti matrix composite

Ti-5Al-5Mo-5 V-1Fe-1Cr Ti matrix composite reinforced with trace TiB and TiC is fabricated via a consumable vacuum arc-remelting furnace in this work. The effects of the reinforcements on the microstructural homogeneity of the composite are investigated. The experiment shows morphology diversity of α grain in the alloy during isothermal compression. However, most of them are in spheroidized shape in the composite. It is revealed that the shape of α grain should be attributed to the increase of the deformation temperature, the refinement of β phase and the load-bearing of TiB. In addition, the tensile properties of the composite undergoing heat treatment are researched. The composite has a good combination of tensile strength and plasticity. Nevertheless, the yield ratio of the composite is as high as 0.97. The dislocation strengthening increases slowly during the strengthening process of tensile test when the dislocations enter the grain boundaries. Owing to the load-bearing of TiB and the refinement of β phase, the yield ratio of the composite is higher than that of the alloy.