镁合金焊接接头耐腐蚀性能研究现状

对近年来镁合金及其焊接接头腐蚀性能的研究现状和最新成果与进展进行了总结,指出了目前在镁合金焊接接头腐蚀研究领域存在的问题与不足,最后分析了镁合金焊接接头腐蚀的研究方向和工作重点。     

镁合金研究开发现状与展望

介绍了镁合金研究开发和应用领域的国内外发展动态,耐热镁合金、耐蚀镁合金、高强高韧镁合金、变形镁合金等高性能镁合金材料的最新发展,镁合金压铸、半固态铸造、挤压铸造、超塑性、冲锻等成形技术的最新开发研究成果,指出了镁合金研究开发的发展趋势,提出了我国在镁和镁合金研究开发和应用领域需要注意的问题。     

Web下的镁合金焊接数据库系统设计

本文成功设计了镁合金焊接数据库系统,这个系统是在Web下基于B/S结构设计的。ASP技术以及网络数据库技术被应用在该系统中,在这个系统中镁合金的焊接性能好坏可以被查询、而且编辑以及系统管理等功能模块也被成功地建立;关于镁合金焊接的所有相关信息都会被合理的、全面的进行解析以及归纳总结,用户可以根据这些结果直接查询到镁合金的焊接性能以及相关的基本数据,所有的实验结果可以被查询到,焊接性能、二元相图以及CCT图等各种信息都被包含其中。这个系统的成功建立对镁合金焊接以及工业制造业具有一定的指导和实用价值,因为它可以实现焊接行业数据的共享。     

AZ31B镁合金/镀锌钢板电阻点焊接头熔核化合物分析

镁合金具有质量轻、拉伸强度高和减振能力强的优点,钢一直在制造业中占主导地位。镁钢异种材料的连接,可以实现汽车构件的轻量化设计,对节能减排有着重要的积极意义。采用KDWJ-17型三相次级整流电阻焊机对2.0 mm厚的AZ31B镁合金和1.0 mm厚的SPHC镀锌钢板进行电阻点焊焊接试验,利用QUANTA200型扫描电子显微镜(SEM)分析接头各区域的组织结构和成分分布,并对接头化合物做热力学分析,研究AZ31B镁合金和SPHC镀锌钢点焊接头中心界面化合物的形成机制。研究结果表明:接头处Fe_2Al_5化合物是形成高强度镁合金与镀锌钢板电阻点焊接头的主要原因;结合Fe-Al二元相图和热力学分析计算,在镁合金和镀锌钢板电阻点焊接头中,Fe_2Al_5在可直接生成的Fe-Al系化合物中为接头相结构的最有利生成相;Fe_2Al_5的结构单元总成键能力在Fe-Al系化合物中其化合物保持自身结构稳定性的能力最强。     

稀土在镁合金中的作用及研究现状

介绍了稀土元素的基本性质及其在镁合金中的主要作用。简述了稀土在Mg-Al系、Mg—Zn系以及Mg—RE系高强度镁合金中的研究和开发现状。指出了含稀土高强度镁合金的发展趋势和研究方向。     

镁合金及其焊接技术

列举了镁合金在各个领域的应用现状,介绍了镁合金焊接的特点,综述了镁合金各种焊接方法的原理、特点及相应的研究现状,并指出了今后镁合金焊接研究的重点。     

碱土元素和稀土元素复合合金化镁合金研究现状及进展

本文介绍了碱土、稀土元素在镁合金中的主要作用及作用机理,简述了碱土、稀土复合合金化的主要发展趋势和研究方向.指出稀碱土镁合金是我国镁合金发展的重要研究方向.     

贵金属合金相图研究的进展及现状

总结了1976～1985年间贵金属合金相图的研究状况,分别介绍了贵金属合金二元系和三元系中的研究进展。并指出到1985年止实验测定贵金属合金相图体系已达768个,比1975年前增加了47.7％。在这十年间,新研究的贵金属合金二元系43个,三元系191个,四元系14个。1975年前研究过的一些体系也得到修正和完善,贵金贵合金相图的计算和实验技术也有很大发展。根据相同的类型,将只含贵金属的二元和现有三元合金相图分为:固液态完全互溶型、偏晶型、包晶型和液态完全互溶固态不完全互溶型。对贵金属合金新材料开发的需要推动了贵金属合金相图的巨大进展,BAPD的出版和实验技术的进步为这种发展创造了条件。最后,指出了今后研究贵金属合金相图的趋势。     

镁合金的合金化阻燃

介绍了含钙、铈和铍镁合金的阻燃效果、表面氧化膜和阻燃机理的研究现状,指出了现在阻燃镁合金研究方面存在的难点以及今后的研究方向.     

镁合金板材研究获重要进展

近期，中科院金属研究所材料环境腐蚀研究中心韩恩厚、陈荣石研究员带领博士生闫宏、吴迪在镁合金相平衡热力学原理和相图计算基础上，通过添加适量的稀土元素，如Y、Nd、Gd等，优化轧制工艺、中间退火和轧制后的最终退火工艺，研究了一系列Mg—Zn—RE合金轧制板材的组织、织构和各向异性。     

Application of free energy-composition diagrams in predicting the sequences of phase transformations in Zr-Nb alloys

The free energy composition diagrams for the Zr-Nb alloy system have been computed from the phase diagram employing Rudman’s technique of phase diagram analysis. The influence of the clustering tendency in the β phase on the sequence of phase transformations in both Zr-rich and Nb (Cb)-rich alloys has been examined. It has been possible to predict different sequences of phase reactions in different ranges of composition and temperature. The experimentally observed phase reactions as reported earlier have been rationalized by the calculated free energy composition plots.     

Extended solid solution and nonequilibrium phase diagram for Ni-Al alloy formed during laser cladding

Due to rapid solidification in laser cladding, the composition of the solute in the cladding alloy often exceeds the solid solubility limit far beyond that expected from the equilibrium phase diagram. Also, the effects of various process parameters on the composition of the cladding alloy depend on the sign of the slope of the equilibrium phase diagram at the nominal composition of the cladding powder. This paper uses a mathermatical model to determine the composition of metastable alloys and to study the effects of various process parameters on the composition of extended solid solution in the cladding alloys of Ni-Al for which the slope of the equilibrium phase diagram is positive at the nominal composition of the Ni-Al cladding powder. The model considers concentration dependent freezing point and nonequilibrium partitioning of solute at the solid-liquid interface. Because of this, nonequilibrium phase diagram can be obtained by following the methodology of this paper.     

Study of the phase equilibria and the decomposition of a supersaturated solid solution in magnesium alloys with aluminum, calcium, and manganese

Magnesium alloys Mg-Al-Ca-Mn having 1 wt % Al, up to 1.8 wt % Mn, and up to 1.6 wt % Ca are studied by optical microscopy, electron microprobe analysis, and electrical resistivity and microhardness measurements. The phase equilibria corresponding to the Al, Ca, and Mn concentration ranges under study were determined and sections of the isothermal tetrahedrons of the Mg-Al-Ca-Mn phase diagram in the Mn-rich region at 450 and 300°C have been constructed. As was found, manganese does not affect the decomposition kinetics of the magnesium supersaturated solid solution in ternary Mg-Al-Ca alloys but increases their hardness.     

Mg-5Gd-3Y-0.8Zr合金的微观组织及耐NaCl溶液腐蚀性能研究

系统研究了Mg-5Gd-3Y-0.8Zr合金的微观组织和耐蚀性能,通过静态失重法测定了其在NaCl溶液中的腐蚀速率。结果表明:铸态合金主要由基体α-Mg和方块状β相(Mg_5Gd、Mg_(24)Y_5)组成,时效处理后分布在晶界处的共晶β相数量明显增加;在NaCl溶液中腐蚀12 h以后镁合金的腐蚀速率明显增加,在3.5%Na Cl(质量分数)溶液中腐蚀24 h后,镁合金已被严重腐蚀,表面布满腐蚀坑和未脱落的白色腐蚀产物;镁合金易产生沿晶腐蚀,方块状共晶β相颗粒可有效阻止表面腐蚀沿晶界向镁合金内部扩展,从而提高镁合金的耐蚀性。     

Friction and Wear Characteristics of Mg-Al Alloy Containing Rare Earths

The influence of rare earth on the friction and wear characteristics of magnesium alloy AZ91 and AM60 were studied. The results show that the wear resistance properties of rare earth magnesium alloys are better than those of matrix alloy under the testing conditions. The anti-wear behaviour of AZ91 alloy is much better than that of AM60 alloy. In dry sliding pmcess, magnesium alloys undergo a transition from mild wear to severe wear. The addition of rare earths refine the structure of alloys, improve the comprehensive behaviors of magnesium alloys,increase the stability of oxidation films on worn surfaces,enhance the loading ability of rare earth magnesium alloys,and delay the transition from mild wear to sevre wear effectively.     

Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy

The effects of samarium（Sm） on microstructure and corrosion resistance of AZ92 magnesium alloy were characterized and analyzed by scanning electronic microscopy, X-ray diffraction, mass loss test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and potentio-dynamic polarization test. The results showed that the added Sm could promote continuous precipitation of β-Mg17Al12 phase in grains, and meanwhile restrain discontinuous precipitation of the same phase along the grain boundaries. Thus, the precipitations distributed more uniformly in the aged AZ92 magnesium alloys. When the content of Sm was 0.5 wt.%, the corrosion resistance of aged AZ92 alloy tended to be the best, which was due to the β-phase distributes more homogeneous reducing the galvanic corrosion. The corrosion product film had more integrality and compactness than AZ92 alloys without Sm. However, it resulted in worse corrosion resistance of AZ92 alloy because of the formation of mass cathodic Al2 Sm phase coming from excess Sm in AZ92 alloy.     

镁合金晶粒异质形核的细化方法

总结了目前镁合金晶粒细化技术中广泛应用的异质形核细化方法,并对其细化机理进行论述。边对边匹配(edge-to-edge matching,简称E2EM)模型与第一性原理计算方法均可以判断镁合金的潜在异质形核核心,是近年来研究异质形核晶粒细化的有效方法。向镁合金中添加溶质元素及中间合金等物质已成为现工业生产中广泛适用的细化技术。为了更好地从微观尺度理解晶粒细化机制,基于密度泛函理论(density functional theory,简称DFT)的第一性原理计算方法不仅能够准确提供界面处原子结合情况,还可以定量预测凝固中异质晶核与初生相之间界面能和黏附功等,为晶粒细化剂的发展提供了理论基础,在镁合金晶粒细化中发挥越来越重要的作用。     

镁合金的研究应用及最新进展

镁合金由于具有质量轻、比强度和比刚度高以及良好的铸造性能等特点,在理论研究和实际应用上引起了人们极大的关注.近年来,世界各国纷纷致力于镁合金的研究开发.本文综述了镁合金的性能特点、镁合金的合金系列、镁合金在汽车、电子等工业上的应用以及镁合金的发展动向,分析了我国镁合金行业的现状和发展前景.     

AZ31镁合金的研究现状

综述了国内外对AZ31镁舍金的研究现状。讨论了主要合金元素对AZ31镁合金的组织和性能的影响,介绍了AZ31镁合金的晶粒细化、塑性成形技术的研究现状。对AZ31镁合金的发展前景进行分析。     

A process for debismuthizing lead with magnesium

Significant amounts of bismuth can be removed from magnesium-lead alloys by crystallization of the intermetallic compounds Mg_{0. 6573}Pb_{0. 3427} and Mg_0.662Pb_0.338in the Mg₂Pb, magnesium plumbide phase field of the Pb-Mg-Bi system. The results of the previous studies have been used to develop a process for debismuthizing lead using controlled conditions for the crystallization of magnesium plumbide from alloys containing 0.03 to 0.06 wt Pct bismuth and magnesium whose concentration is determined by the relationship wt Pct Mg = 2.9 + 20 x wt Pct Bi. A flow diagram showing the sequence of operations is presented together with a material balance, which was established from data obtained from individual experiments simulating the previously mentioned unit operations, with a final product containing less than 0.0010 wt Pct Bi. The process also includes the recycling of magnesium recovered by vacuum distillation. Additional procedures are included to extend the process to treat alloys containing up to 1.5 wt pct bismuth.