Improvement of microstructure and mechanical properties of Al−Cu−Li−Mg−Zn alloys through water-cooling centrifugal casting technique

The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experimental results demonstrated that compared with the gravity casting technique,the water-cooling centrifugal casting technique significantly reduces porosity,refinesα(Al)grains and secondary phases,modifies the morphology of secondary phases,and mitigates both macro-and micro-segregation.These improvements arise from the synergistic effects of the vigorous backflow,centrifugal field,vibration and rapid solidification.Porosity and coarse plate-like Al13Fe4/Al7Cu2Fe phase result in the fracture before the gravity-cast alloy reaches the yield point.The centrifugal-cast alloy,however,exhibits an ultra-high yield strength of 292.0 MPa and a moderate elongation of 6.1%.This high yield strength is attributed to solid solution strengthening(SSS)of 225.3 MPa,and grain boundary strengthening(GBS)of 35.7 MPa.Li contributes the most to SSS with a scaling factor of 7.9 MPa·wt.%^(-1).The elongation of the centrifugal-cast alloy can be effectively enhanced by reducing the porosity and segregation behavior,refining the microstructure and changing the morphology of secondary phases.

Effect of water content on corrosion inhibition behavior of self-assembled TDPA on aluminum alloy surface

Self assembled monolayers （SAMs） of 1-tetradecylphosphonic acids （TDPA, CH3（CH2）13P（O）（OH）2 ） were formed on the 2024 aluminum alloy surface in TDPA-containing ethanol-water solutions with different water content. The adsorption and corrosion protection properties of the SAMs for 2024 alloy in 0.1 mol/L H2SO4 solution were examined and characterized by potentiodynamic polarization, electrochemical impedance spectrum （EIS）, Fourier transformed infrared spectroscopy （FTIR）, Auger electron spectra （AES） and atomic force microscopy （AFM）. FTIR and AES results show that the TDPA molecules were successfully adsorbed on the 2024 aluminum alloy surface, and the density of the SAMs increased with the increasing water content in the assembly solution. The results of electrochemical studies and corrosion morphologies observed by AFM show that a 4 h modification resulted in maximal inhibition efficiency, and the higher the water content in the assembly solution is, the better the inhibition performance of the SAMs can be achieved. The effect of water content in TDPA solutions on the performance of the SAMs is related to the hydration reaction of the metal surface.

Optimal Management Helps Reducing Risks for Potable-Water Resources in Albania

Albania is located on the eastern shore of the Adriatic and Jon Sea, south of former Yugoslavia, north of Greece, and west of Macedonia. It is divided into three agro-ecological zones based on climate, soils and vegetation： the fertile coastal plains, the intermediate hilly region, and the non-arable mountain zones. Annual rainfall varies from 800 to 2,000 mm in coastal areas to 1,600 to 2,000 mm in the hilly regions and up to 3,000 mm in the mountains. Rainfall is concentrated mainly in the winter, and less than 20 percent of annual rainfall occurs in the six-month period between April and September. Studies indicate that available sources of supply could provide more than enough to satisfy the country＇s overall water demand. In many cities, water availability at the source is about 500-700 litres per capita per day, but leaks and waste mean that only a small fraction of water produced is consumed. The paper research concludes that the Albanian government should： （1） Introduce and implement new anti-corruption laws to increase the market transparency; （2） Continue the ongoing institutional and economical reform to deliver better legal institutions and market efficiency; （3） Reduce anti-competitive practices such as government monopoly in some sectors and privatize all the strategic sectors; and （4） Urgently develop with the help of International Monetary Fund, new projects regarding infrastructure with clear the National Investment Promotion Agency from the bureaucratic procedures and further increase the budget to improve the whole internal infrastructure.

我国东北北部中晚古生代地层

本文涉及的范围为我国东北地区的北部,包括黑龙江省、吉林省的大部分及辽宁省的西北部。 解放以前,本区在区域地层研究方面基本上是个空白区。 解放后,特别是无产阶级文化大革命以来,在毛主席和中国共产党的英明领导下,通过生产、科研、教学的密切结合,使得本区的地层研究工作有了迅速进展,取得了丰硕的成果。建立了前寒武纪、古生代、中生代及新生代由老到新的区域地层系统。