Al/a-Si:H界面反应和热处理行为光发射研究

国家自然科学基金

Au、Al/a-Si:H热退火行为研究

于2010-11-23批量导入

Microstructures and mechanical properties of as-cast Mg–5Al–0.4Mn–xNd (x=0, 1, 2 and 4) alloys

Mg-5Al-0.4Mn-xNd (x=0, 1, 2 and 4wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results demonstrated that Al11Nd3 phase was formed and mainly aggregated along the grain boundaries with the addition of Nd. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content.

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.

Effect of substituting cerium-rich mischmetal with lanthanum on microstructure and mechanical properties of die-cast Mg-Al-RE alloys

Die-cast Mg-4Al-4RE-0.4Mn (RE = Ce-rich mischmetal) and Mg-4Al-4La-0.4Mn magnesium alloys were prepared successfully and their microstructure, tensile and creep properties have been investigated. The results show that two binary Al-RE phases, Al11RE3 and Al2RE, are formed along grain boundaries in Mg-4Al-4RE-0.4Mn alloy, while the phase compositions of Mg-4Al-4La-0.4Mn alloy mainly consist of alpha-Mg phase and Al11La3 phase. And in Mg-4Al-4La-0.4Mn alloy the Al11La3 phase occupies a large grain boundary area and grows with complicated morphologies, which is characterized by scanning electron microscopy in detail. Changing the rare earth content of the alloy from Ce-rich mischmetal to lanthanum gives a further improvement in the tensile and creep properties, and the later could be attributed to the better thermal stability of Al11La3 phase in Mg-4Al-4La-0.4Mn alloy than that of Al11RE3 phase in Mg-4Al-4RE-0.4Mn alloy.

Preparation of W-Al alloys by mechanical alloying

W1-xAlx (x=0-0.86) alloys were synthesized by mechanically alloying the pure metal powder mixtures at designated compositions by conventional high-energy ball milling. The W-Al alloys were stable under high pressure and high temperature. The alloys were lighter than W. The hardness and oxidation resistance of the alloys was greatly improved compared to both W and Al. (C) 2002 Elsevier Science B.V. All rights reserved.

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。

Macro-segregation of multi-component alloys in shape casting simulation

The objective of this work is to present a new scheme for temperature-solute coupling in a solidification model, where the temperature and concentration fields simultaneously satisfy the macro-scale transport equations and, in the mushy region, meet the constraints imposed by the thermodynamics and the local scale processes. A step-by-step explanation of the macrosegregation algorithm, implemented in the finite volume unstructured mesh multi-physics modelling code PHYSICA, is initially presented and then the proposed scheme is validated against experimental results obtained by Krane for binary and a ternary alloys.