交通运输用导电铝合金的应用现状及研究进展

随着经济社会的不断发展,城市轨道交通建设以及电动汽车、新能源交通工具的逐渐普及,铝合金导线在交通运输网络的电力传输和交通装备运行等方面的用量日益增多,但铝合金导线因其本征的电阻在电力传输过程中仍存在着很大程度的能源损耗,如何提升导电率的同时保证铝合金导体材料的强度是研究的长期难点。本文结合导电铝合金的发展现状及主要合金体系,探讨了铝合金导体材料的强度-电导率制约关系,总结了当前协同改善强度和导电率、制备高强高导铝合金的研究进展,归纳了几类主流的改善方法,即微合金化、热处理工艺优化、大塑性变形制备超细晶、制备铝基复合材料、熔体净化和提纯、沿平行电流方向引入细长晶等,最终展望了高强高导铝合金的未来发展。

中和料液梯次循环式生产味精晶型的探讨

介绍了料液梯次循环式生产细长晶味精和粗壮味精的基本工艺流程和实现正常生产所要控制的重要指标,即含量浓度比。重点论述了生产细长晶和粗壮型味精的操作要点,介绍了细长晶味精和粗壮型味精的基本数据。

Effects of neodymium addition on microstructure and mechanical properties of near-eutectic Al-12Si alloys

The microstructure and mechanical properties of near-eutectic Al-12 Si alloys modified with 0-0.4% Nd（mass fraction） were investigated. The results indicate that a submicro- or nano-sized Al2 Nd phase is observed in the modified alloy with 0.3% Nd. The morphology of the α（Al） phase is significantly refined in the Nd-modified alloys. The primary Si morphology simultaneously changes into a fine, particle-like morphology, and the morphology of eutectic Si becomes fine-fibrous instead of coarse-acicular. Relatively few growth twins are observed on the surface of the Si plate in the Al-12Si-0.3Nd alloy at the optimal modification level. The mechanical property test results confirm that the mechanical properties of the as-cast Al-12 Si alloys are enhanced after the Nd addition, with optimal ultimate tensile strength（UTS） of 252 MPa and elongation（EL） of 13% at an Nd content of 0.3%. The improved mechanical properties are attributed to the refined morphology of Si phase and the formation of the Al2 Nd phase.

Effects of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification

In order to understand the effect of geometric parameters and axial magnetic field on buoyant-thermocapillary convection during detached solidification, a series of threedimensional numerical simulations were conducted by the finite-difference method. The results indicate that the stable flow is observed when the Marangoni number （Ma） is small; however, when the value of Ma increases and exceeds a threshold value, the stable steady flow transits to be unstable flow. As the height of the melt increases, the flow is enhanced at first and then gets weakened. As the width of gap decreases gradually, the strength of flow is enhanced. The approach of using axial magnetic field is an effective way to suppress the buoyant-thermocapillary convection. As the magnetic field strength increases, the inhibition is enhanced. The critical Marangoni number increases slightly with a greater melt height, a narrower width of gap, and a more strength of magnetic field.

Thermal stability evaluation of nanostructured Al6061 alloy produced by cryorolling

Grain growth of nanostructured Al6061produced by cryorolling and aging process was investigated during isothermalheat treatment in100?500°C temperature range.Transmission electron microscopy(TEM)observations demonstrate that aftercryorolling and aging at130°C for30h,the microstructure contains61nm grains with dispersed50?150nm precipitates and0.248%lattice strain.In addition,an increase in tensile strength up to362MPa because of formation of fine strengtheningprecipitation and nano-sized grains was observed.Thermal stability investigation within100?500°C temperature range showedrelease of lattice strain,dissolution of precipitates and grain growth.According to the X-ray diffraction(XRD)analysis,Mg2Siprecipitates disappeared after annealing at temperatures higher than300°C.According to the results,due to the limited grain growthup to200°C,there would be little decrease in mechanical properties,but within300?500°C range,the grain growth,dissolution ofstrengthening precipitates and decrease in mechanical properties are remarkable.The activation energies for grain growth werecalculated to be203.3kJ/mol for annealing at100?200°C and166.34kJ/mol for annealing at300?500°C.The effect ofprecipitation dissolution on Al lattice parameter,displacement of Al6061(111)XRD peak and Portevin?LeChatelier(PLC)effect onstress?strain curves is also discussed.

Relationship between solid/liquid interface and crystal orientation for pure magnesium solidified in fashion of cellular crystal

The relationship between the solid/liquid interface and the crystal orientation for pure magnesium,which grows in fashion of cellular crystal in unidirectional solidification,was investigated.The results show that the energy of the solid/liquid interface is the lowest during cellular crystal growth of pure magnesium;and the solid/liquid interface is covered by the basal face{0001}and by the crystal face made up of three atoms located at the orientation{0001}0100and two atoms located at the inner of magnesium crystal cell.The strongest bond is formed in the direction of 61.9°viating from the growth direction,and the second strong bond is formed in the directions of 8.5°d 47.7°espectively,deviating from the growth direction.The angle between the basal face{0001} and the growth direction is 61.9°he theoretical analysis results are basically consistent with the experimental results from SUSUMU et al.

Expression and effect of basic fibroblast growth factor on human cataract lens epithelial cells

OBJECTIVE: To detect the expression of basic fibroblast growth factor (bFGF) in human ocular tissues, and to assess the effect of bFGF on the proliferation of human cataract lens epithelial cells (LECs) and its correlation with age. METHODS: Enucleated eyes were subjected to immunostaining for bFGF protein. Human cataract LECs were cultured in vitro, and treated with bFGF for 48 hr. Proliferation was estimated by the positive area ratio of proliferating cell nuclear antigen (PCNA) in immunohistochemistry. RESULTS: bFGF protein was found in various human ocular tissues. bFGF stimulated human cataract LEC proliferation, and there was an age-related decrease in responsiveness of human cataract LECs to bFGF (P