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Microstructure and mechanical responses of A357 aluminum alloy welding wires after different degrees of strain were studied. It is found that the grains are elongated and refined along the drawing direction, accompanying with cell structures and sub-grains with strain increasing. Meanwhile, the main contributions to the fibrous texture are Cube, Goss and Copper, i.e., and textures. With the increase of drawing strain, the volume fraction of the Copper texture first increases and then decreases, while that of the Goss texture increases monotonously. The yield strength sharply increases at low drawing strain, after reaching the maximum value of 144.7 MPa at the strain of 0.32 and it decreases slightly due to dynamic recrystallization. Interestingly, the elongation of the cold-drawn wires decreases steadily from 24.4% to 2.3% throughout the entire drawing process. In addition to the grain boundary strengthening and dislocation strengthening, the yield strength of the cold-drawn A357 wires is also impacted by the texture.

Wire-feed electron beam additive manufacturing (EBAM) is a promising manufacturing process for fabrication large-scale, fully dense and near net shape metallic components. However, limited knowledge is available on the wire-feed EBAM process of titanium alloys. In this work, the Ti-5Al-2Sn-2Zr-4Mo-4Cr near β titanium alloy sample was fabricated by the EBAM process and the effect of subtransus solution and aging treatment on the microstructure evolution and mechanical properties was investigated. The results reveal that the volume fraction of the primary α decrease dramatically from 48.6% to 8.9% with increasing the solution temperature from 750 °C to 850 °C. The ultimate tensile strength and yield strength increase monotonously with increasing of the solution temperature, while the elongation and reduction of area change conversely. The thickness of the secondary α (αS) increases significantly from 28.6 nm to 120.1 nm with the aging temperature increasing from 550 °C to 710 °C. The volume fraction and thickness of αS are sensitive to the aging temperature and strongly influence the mechanical properties. The quantitative relationship between the microstructure and mechanical properties was established. As a good result, the tensile properties of the post-deposition heat treated alloy at 400 °C can meet the standard requirements for wrought counterpart.

Ti-Si-C composite powder was designed as raw material for laser deposition, and fabricated into quasi-spherical powder particles. On this basis, Ti6Al4V/(TiC+Ti3SiC2) system functionally graded material (FGM) was designed and fabricated using pure Ti powder and the fabricated Ti-Si-C composite powder. The microstructures of the gradient layers were analyzed by a scanning electron microscope (SEM) equipped with an X-ray energy dispersive spectrometer (EDS). An X-ray diffraction (XRD) spectrometer and a transmission electron microscope (TEM) were used for determination of the reaction products in the gradient layers. In-situ chemical reactions took place between elements Ti, Si and C in the deposited layers, and the reaction products included TiC and Ti3SiC2 ceramics as well as Ti5Si3 compound. Finally, Ti6Al4V/(TiC+Ti3SiC2) system FGM with a planar size of 25 mm × 50 mm was fabricated and the total thickness of all the graded layers was 2.2 mm. The average three-point bending strength of the overall Ti6Al4V/(TiC+Ti3SiC2) system FGM was high up to 995 MPa at room temperature, and the outermost layer exhibited the microhardness of 647.5 HV. Keywords: Additive manufacture, Ti-Si-C, In-situ reaction, Laser deposition, Mechanical properties