The tensile performance of Ti6Al4V alloy lattice structure was investigated. Firstly, a face center cubic unit cell with vertical struts (F2CCZ) lattice structure was designed. Then, the structures were fabricated by selective laser melting (SLM) with different aspect ratios. Subsequently, the SLM-ed alloys were subjected to double solution-aging to homogenize the microstructure and release residual stress. It is shown that there is only acicular α′ martensite with high dislocation density in the SLM-ed alloy, while the heat-treated alloy has α and β phases (there are multi-scale α laths and nano-scale β particles), and the orientation relationship between the two phases is: [113]_β//[1210]_α. The tensile strength of the HT-ed alloys presents a significant increase from 140 ± 18 MPa in the SLM-ed state to 229 ± 5.1 MPa with an aspect ratio of 4. It indicates that the special heat treatment regime can not only homogenize the microstructure of the SLM-ed alloy, but also improve the tensile strength.

Selective laser melting (SLM) currently uses the micro-fine spherical powder prepared by gas atomisation as a raw material. However, the spherical powder is expensive. In order to reduce the cost, this study first ball mills the pure titanium (CP-Ti) powder of hydrogenation-dehydrogenation (HDH). At a high speed and within a short period, the particle size distribution of the powder at a high rotation speed for 15 min is 12–45 μm with an angle of repose 34.3°. Then, the ball milling of titanium was mixed spherical powder with a wide grain size range up to 100 μm. This study presents the results of using SLM to produce CP-Ti parts starting from powder with mixed powder, in a different ratio between modified powder and spherical powder. The ultimate tensile strength (UTS) of SLM-parts of 8:2 ratio has been improved to 507 MPa, and the UTS of parts of 7:3 ratio has been improved to 522 MPa.

Porous titanium is a functional structural material with certain porosity, which is prepared from titanium powder and titanium fiber. In order to study the porosity, phase structure, microstructure, sintering mechanism and mechanical properties of porous titanium obtained by spark plasma sintering of a Ti powder–fiber mixture at different sintering temperatures, a spherical titanium powder (D₅₀ of 160 μm) was prepared via plasma rotating electrode processing, and titanium fiber (average wire diameter of fiber of 110 μm) was prepared by drawing, and they were mixed as raw materials according to different mass ratios. Porous titanium with a fiber–powder composite porous structure was prepared by spark plasma sintering at sintering temperatures of 800 °C, 900 °C and 1000 °C under a sintering pressure of 20 MPa. The results showed that there were no new phases occurring in porous titanium with porosity of 1.24–24.6% after sintering. Titanium fiber and titanium powder were sintered using powder/powder, powder/fiber and fiber/fiber regimes to form composite pore structures. The mass transfer mechanism of the sintered neck was a diffusion-dominated material migration mechanism during sintering. At higher sintering temperatures, the grain size was larger, and the fiber (800 °C; 10–20 μm) was finer than the powder (800 °C; 10–92 μm). The stress–strain curve of porous titanium showed no obvious yield point, and the compressive strength was higher at higher sintering temperatures. The results of this paper can provide data reference for the preparation of porous titanium obtained by spark plasma sintering of a Ti powder–fiber mixture.

Porous titanium samples with a porosity of 1.34~15.54% were prepared by a spark plasma sintering (SPS) process at sintering temperatures of 800 °C, 850 °C and 900 °C, and a sintering pressure of 10 MPa. The microstructures and fracture morphology of the samples were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The compressive strength and elastic modulus were likewise measured. The results showed that no new phase occurred after the samples were sintered, and the main phases were α phase of hcp structure. The porosity of the samples decreased significantly with the increase of sintering temperature. At 800 °C, the sample phase was dominated by equiaxed α. There were more irregular coarse pores in the samples. At 850 °C, the microstructure was mainly zigzag α, and the pores were finely and relatively uniform in distribution. At 900 °C, the sample’s structure transformed into a dense sheet-like α. The sample’s densities increased and the pores disappeared. The room temperature compression test showed that the porous titanium sintered by SPS had excellent compressive strength. The yield strength, compressive strength, compressive strain and elastic modulus were 81.85~122.36 MPa, 161.65~498.86 MPa, 36.75~59.97% and 2.79~4.22 GPa, respectively.

In order to study the permeability characteristics of heavy metal ions contaminated red clay and explore the rapid detection of permeability of heavy metal contaminated red clay. Through variable-head permeability test and electrical resistivity test (different voltages and methods), the effects of Cu2+ concentration and initial water content on hydraulic conductivity characteristic and resistivity of contaminated red clay was systematically investigated. The relationship between permeability characteristic and electrical resistivity was further explored by taking Cu2+ concentration and moisture content as the intermediate variable. The obtained results indicate that the different voltage has no obvious effect on the resistivity of the samples. The four-phase electrode method is more accurate than the two-phase electrode method. With increasing Cu2+ concentrations the hydraulic conductivity of specimens increases, however the permeability coefficient of contaminated soil decreases with increasing initial water content. In the resistivity test, with increasing of Cu2+ concentrations and water content, the resistivity of samples presented a downward trend, which is decreased sharply at first and then tended to be gentle. The relationship between hydraulic conductivity and resistivity of contaminated soil showed a good fitting curve no matter in different Cu2+ concentration or in different water content, but the fitting curves of them presented opposite trend.

Ti–1Al–8V–5Fe (Ti-185) is a unique low-cost β-Ti alloy, containing lower cost alloying elements, notably Fe, as compared to Ti–10V–2Fe–3Al (Ti-1023) and Ti–5Al–5V–5Mo–3Cr (Ti-5553) while offering high strength. However, with higher Fe content (>5 at.-%), the ‘β-flecks’ are prone to form because strong segregation in traditional casting, which seriously deteriorates the mechanical properties of the alloys. In this work, Spark plasma sintering (SPS) was successfully used to produce Ti-185 components starting from elemental Ti and Al powders, and a V–Fe master alloy powder with different particle size (106, 45, and 23 μm). SPS can be used to produce a very fine grain microstructure with decreasing particle size master alloy powder and non-detrimental Fe segregation, and which result in a significant improvement of the mechanical properties. As the particle size of the FeV₈₀ powder decreases, the compressive strength, yield strength and compressive strain of the alloy gradually increase.