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In this study, Mg-Zn-Y-Nd alloy micro-tubes with an outer diameter of φ2.46 mm and a wall thickness of 0.14 mm were successfully prepared using an improved technique including hot extrusion with water cooling, multi-pass cold drawing and final annealing treatment. The outer diameter error, inner diameter error and wall thickness error of the cold drawn micro-tubes were 0.58%, 0.36% and 3.43%, respectively. After final annealing at 350 °C for 60 min, the micro-tubes showed refined microstructure with an average grain size of 8.6 μm, a weak texture of the rare earth texture or recrystallization texture, and homogeneously distributed fine second phase particles. The annealed micro-tubes exhibited significantly improved mechanical properties with a yield strength of 240.1 ± 6.0 MPa, an ultimate tensile strength of 319.9 ± 6.0 MPa and a breaking elongation of 22.2 ± 1.0%. Meanwhile, the typical characteristic of ductile morphology could be observed for the fractured specimens. In addition, the annealed micro-tubes also had better corrosion resistance and showed a uniform corrosion morphology. • The thin-walled Mg alloy micro-tubes were prepared by an improved method. • The rare earth texture and recrystallization texture were formed in the annealed microtube. • The annealed micro-tubes showed weakened texture. • High strength and large elongation of the annealed micro-tubes were achieved. [ABSTRACT FROM AUTHOR]

• The K sat of Zn-contaminated loess increases with time, while a decreasing trend for Cu-contaminated loess. • The hydrolysis of Zn2+ and the DDL effect are beneficial to the development of water passage. • The Cu 2 O precipitation in the Cu-contaminated loess is the main controlling factor for the weakening of pore connectivity. • The relationship among geochemical action, microstructure evolution, and seepage behavior of heavy-metal contaminated loess is revealed. Heavy metal contamination in soils can pose severe challenges to the safety of geotechnical engineering projects. Loess, which is widely distributed in Northwest China, is a preferred engineering construction material for anti-fouling barriers. Therefore, research on the influence of heavy metal ions on its seepage performance is urgently required. To obtain new insights into the seepage behavior of heavy metal-contaminated loess and its underlying geochemical mechanism, laboratory investigations were performed on the saturated hydraulic conductivity (K sat), leaching, and microstructural characteristics of loess contaminated with Cu2+ and Zn2+. The results indicate that the hydrolysis of Zn2+ creates an acidic environment, which promotes the dissolution of carbonate minerals in loess, enhances the leaching capacity, and leads to the quantitative transformation of small pores (2–8 μm) to mesopores (8–32 μm). Meanwhile, the alternating adsorption of Zn2+ and its diffuse double-layer effect compresses the diffusion layer, increasing the abundance of free water channels. Thus, the K sat of Zn-contaminated loess increases by 81.2% during the seepage period. As for Cu-contaminated loess, its seepage behavior is the opposite of that of Zn-contaminated loess, with a K sat decrease of nearly 50%. The primary factor controlling this phenomenon is the formation and enrichment of Cu 2 O in the lower part of the soil, which inhibits the enlargement of pores and reduces the effective connectivity of pores. The findings of this work provide insight into the seepage behavior of saturated loess under erosion by heavy metals and the underlying geochemical mechanism thereof. [ABSTRACT FROM AUTHOR]