The microstructures and mechanical properties of cast Mg-Zn-Al-RE alloys

The microstructures and mechanical properties of cast Mg-Zn-Al-RE alloys with 4 wt.% RE and variable Zn and At contents were investigated. The results show that the alloys mainly consist of alpha-Mg, Al2REZn2, Al4RE and tau-Mg-32(Al,Zn)(49) phases. and a little amount of the beta-Mg17Al12 phase will also be formed with certain Zn and At contents. When increasing the Zn or At content, the distribution of the Al2REZn2 and Al4RE phases will be changed from cluster to dispersed, and the content of tau-Mg-32(Al,Zn)(49) phase increased gradually. The distribution of the Al2REZn2 and Al4RE phases, and the content of beta- or tau-phase are critical to the mechanical properties of Mg-Zn-Al-RE alloys.

稀土对Al-Mg-Si系合金结构和性能的影响

本文用ＸＲＤ和ＳＥＭ方法研究了稀土对Ａｌ－Ｍｇ－Ｓｉ系合金微观结构的影响，同时还测定了这些合金的耐腐蚀及力学性能。结果表明，该体系的稀土铝合金中大约含０．１０％稀土就可以细化组织，提高使用性能。具有很好的应用前景。

稀土对Al-Mg-Si建筑铝型材性能的影响

研究了稀土对Ａｌ－Ｍｇ－Ｓｉ建筑铝型材性能的影响。其微观结构及组成采用金相显微镜、扫描电子显微镜及光电子能谱分析，同时测量了样品的机械强度和耐蚀性能。结果表明其挤压预热温度降至４３０℃，速度达到６．２８～７．３６ｍｍ／ｓ，在Ａｌ－Ｍｇ－Ｓｉ材料中加入适量的稀土可以细化晶粒并且增加了材料的机械强度和耐蚀性能。

稀土对高强Al-Zn-Mg-Cu合金耐蚀性能的影响

采用化学失重法，考察了稀土对Al－Zn－Mg－Cu高强铝合金耐腐蚀性能的影响。研究结果表明，在不同介质中，加稀土的Al-Zn-Mg-Cu比Al-Zn-Mg-Cu高强铝合金有较高的耐腐蚀性能，在还原性介质中的耐腐蚀性更好。稀土含量控制在0．05％为宜。

稀土对Al-Mg-Si合金性能影响和稀土作用机理研究

本文研究了稀土对铝镁硅合金性能的影响通过添加稀土改善合金的综合性能,提高合金的成品率,表面光泽性和致密度,讨论了稀土对铝镁硅合金的作用机理,为稀土在铝镁硅合金型材中的推广应用提供了有力的实验依据。

Electron-impact single ionization of Mg and Al+

Theory and experiment are compared for the electron-impact single ionization of Mg and Al+. Nonpertur- bative R matrix with pseudostates RMPS and time-dependent close-coupling TDCC calculations have been carried out that exhibit large reductions from perturbative distorted-wave results of 38% for Mg and 20% for Al+. Experimental single-ionization data available for Mg and Al+ are in reasonable accord with distorted-wave data and lie substantially above the new theoretical results. Rate coefficients, necessary for the collisional- radiative modeling of Mg and Al plasmas were generated from the RMPS ionization cross sections. In the collisional-ionization region near the ionization threshold, the resulting rates were found to be up to two times lower for Mg and three times lower for Al+ than the rates generated from experimental data.

Estudio de adhesibilidad entre una aleación de aluminio A319.0 y una camisa de aluminio base Al-Si-Cu-MG. para aplicaciones automotrices

Teis ( Maestro en Ciencias de Ingeniería Mecánica con Especialidad en materiales) U.A.N.L.

Effect of mechanical coating with Ni and Ni-5% Al on the structure and electrochemical properties of the Mg-50% Ni alloy

The Mg-Ni metastable alloys (with amorphous or nanocrystalline structures) are promising candidates for anode application in nickel-metal hydride rechargeable batteries due to its large hydrogen absorbing capacity, low weight, availability, and relative low price. In spite of these interesting features, improvement on the cycle life performance must be achieved to allow its application in commercial products. In the present paper, the effect of mechanical coating of a Mg-50 at.% Ni alloy with Ni and Ni-5 at.% Al on the structure, powder morphology, and electrochemical properties is investigated. The coating additives, Mg-Ni alloy and resulting nanocomposites (i.e., Mg-Ni alloy + additive) were investigated by means of X-ray diffraction and scanning electron microscopy. The Mg-Ni alloy and nanocomposites were submitted to galvanostatic cycles of charge and discharge to evaluate their electrode performances. The mechanical coating with Ni and Ni-5% Al increased the maximum discharge capacity of the Mg-Ni alloy from of 221 to 257 and 273 mA h g(-1), respectively. Improvement on the cycle life performance was also achieved by mechanical coating.

Influence of iron addition on the microstructure and the electrochemical corrosion of Al-Zn-Mg alloys

The effect of Fe addition on the microstructural properties and the corrosion resistance of Al-Zn-Mg alloys submitted to different heat treatments (cast, annealed and aged), has been studied in chloride solutions using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), cyclic polarization (CP) and open circuit potential (o.c.p.) measurements. The presence of 0.3% Fe in the alloy limited the growth of the MgZn2 precipitates, both in the annealed and in the quenched specimens. No effect of Cr on the grain size in the presence of Fe was found because of the accumulation of Cr in the Fe-rich particles. Fe in the Al-Zn-Mg alloys also made them more susceptible to pitting. Pitting occurred mainly near the Fe-rich particles both, under o.c.p. conditions in O-2-saturated solutions and during the CP.

Effect of welding on the microstructure and electrochemical corrosion of Al-Zn-Mg-Fe alloys

The effect of gas tungsten are welding on the microstructure and electrochemical corrosion of Al-Zn-Mg-Fe alloys submitted to different heat treatments (as fabricated, annealed and aged) has been studied using optical microscopy, SEM, TEM, EDX, cyclic voltammetry and corrosion potential measurements in chloride solutions. The electrochemical techniques were very sensitive to the change in the phase compositions produced by welding. Welding caused a decrease in the mean grain size, in the hardness and in the corrosion resistance of the age-hardened alloys. The structure of the latter became strongly altered by welding to lead to phase compositions very close to those of the cold rolled and annealed specimens. (C) 2000 Elsevier B.V. Ltd. All rights reserved.