铝锂合金研究进展和航空航天应用

概述了国内外铝锂合金的研究历史和发展现状,以及铝锂合金在航空航天领域的应用情况。回顾和总结国外新型铝锂合金的特征和加工制造技术进展,介绍了国外新型铝锂合金的生产情况。总结和分析了我国铝锂合金制造技术发展和最新应用,指出了我国铝锂合金发展中存在的不足。最后探讨了我国铝锂合金的发展趋势和研究发展方向。     

快速凝固铝锂合金研究进展

快速凝固铝锂合金是一种低密度、高强度、高弹性模量的引入注目的新型航空航天结构材料。本文概述了快速凝固铝锂合金的特点、基本制备工艺及力学性能，着重综述了提高锂含量，减少氧化物的危害和研制离锆的铝锂合金这三个方面的最新进展，并简要介绍了应用现状和发展前景。     

铝锂合金研究进展

回顾了铝锂合金的发展历史,按时间顺序和性能特点将铝锂合金划分成了三代,并重点介绍了第三代铝锂合金的发展情况,其最引人瞩目的是高强可爆铝锂合金的兴起和低各向异性厚板材的生产,分析认为,第三代铝锂合金的发展趋势是有针对性地提高合金的某方面性能。     

铸造铝锂合金强韧化研究现状与展望

铸造铝锂合金具有低密度、高模量、高比强度和比刚度等优点,适用于制备复杂薄壁构件,是航空航天、国防军工行业理想的结构材料。基于铸造铝锂合金的组织特征,探索提升合金强塑性的有效途径,可以夯实铸造铝锂合金在轻量化领域的优势地位,扩大其应用范围。首先,概括了国内外铸造铝锂合金的发展历程,归纳了铸造铝锂合金的组织特征与强韧化机制。然后,围绕铸造铝锂合金强韧化研究的最新进展,系统分析了合金化与热处理对铸造铝锂合金微观组织及力学性能的影响规律,总结了提升铸造铝锂合金强塑性的主要途径。最后,面向铸造铝锂合金实际工程需求,对其强韧化处理中尚存的科学难题与未来的研究方向进行了探讨与展望。     

铝锂合金研究开发的历史与现状

综述了国内外关于铝锂合金的研究概况；对铝锂合金的实际应用进行了简要归纳；分析和评述了铝锂合金今后的发展态势。     

航天轻型结构材料——铝锂合金的发展

概述了铝锂(Al-Li)合金的发展历史,总结了其发展趋势:(1)超强、超韧性方向发展;(2)超低密度化发展;(3)改善铝锂合金的焊接性能;(4)改善铝锂合金的各向异性;(5)改善铝锂合金的热稳定性.指出了提高铝锂合金性能的主要途径:(1)微合金化;(2)形变热处理;(3)纯净化;(4)再结晶、在不同方向上拉伸或冷轧、减小变形量等.介绍了铝锂合金的制造方法及其在航天方面的应用.     

铝锂合金焊接技术的研究现状分析

铝锂合金作为轻质、高性能材料,得到广泛的应用,铝锂合金连接质量和应用受到焊接方法的影响,采取不同焊接方法对于连接区域性能产生不同影响,可能会造成焊接区域性能改变,因此焊接方法成为人们研究的热门问题。基于此,该文先对铝锂合金成分进行了深入分析,然后对铝锂合金焊接技术进行详细分析。以期通过采取合适的焊接技术,可以减少焊接方法对于铝锂合金质量的影响,保证焊接连接区域性能满足质量要求,推动铝锂合金的广泛应用。     

焊后热处理对2091铝锂合金接头机械性能的影响

研究了２０９１铝锂合金焊后热处理对焊接接头机械性能的影响，结果表明，对２０９１铝锂合金进行焊后热处理，可以显著提高其接头强度，对塑性的影响不明显。     

新型铝锂合金的研究和发展

综述了铝锂合金的研究概况,介绍了新型铝锂合金的成分、性能、组织特征和提高强韧性的途径,并针对铝锂合金目前存在的问题,提出了今后的研究方向.     

快速凝固粉末铝锂合金的研究及发展(一)

本文综述了快速凝固粉末铝锂合金在成分选定、粉末的制取和成型、合金组织与性能等几方面的主要研究成果。分析了粉末冶金铝锂合金的发展前景和趋势。简要介绍了铝锂合金粉末冶金的两种新技术的基本原理。     

NOTCH SENSITIVITY OF ALUMINUM-LITHIUM ALLOYS IN FATIGUE

In order to evaluate the notch fatigue strength and notch sensitivity of aluminum-lithium, 2090 and 8090, alloys, rotary bending fatigue tests have been carried out using circumferentially notched specimens with different stress concentration factors. The results were compared with those of traditional aluminum, 2024T4 and 7075-T6511, alloys. It was found that 2090 and 8090 alloys showed superior notch fatigue strength in comparison to the conventional aluminum alloys. The notch sensitivities to the crack initiation limit of the aluminum-lithium alloys were lower than those of 7075-T6511, while they were nearly equal to those of 2024T4 for blunt notches. The notch sensitivities to the crack propagation limit were also lower in aluminum-lithium alloys, in particular the 8090 alloy, than in the conventional aluminum alloys. It was suggested that the decreased notch sensitivities of the aluminum-lithium alloys were attributed to both the crack propagation mode and the excellent propagation resistance related to their microstructures.     

Design and manufacture of a superplastic-formed aluminum-lithium component

The phenomenon of superplasticity in metallic alloys is briefly described. The design, manufacture and post-forming analyses are described of a complex shape produced by superplastic forming using the aluminum-lithium alloy 2090.     

铝—锂合金的研究进展

本文评述了近年来国外有关铝—锂合金的物理冶金、力学性能和强化机制等方面的文献资料,并提出了尚待解决的问题和需要开展的工作。     

CASTING ALUMINUM-LITHIUM ALLOYS IN OPEN ATMOSPHERE

The increasing need for lightweight and cost-effective materials for structural applications has resulted in significant improvements and development of new aluminum alloys for structural applications. Lithium addition to aluminum has the potential for providing a class of high strength alloys with exceptional properties suitable for weight-critical and stiffness-critical applications. Casting of aluminum-lithium alloys presents a variety of problems and high-quality ingots are not readily obtainable through conventional procedures. The reactive nature of lithium necessitates the need for inert gas treatments in order to ensure melts of acceptable quality. Exploitation of the properties of these alloys is possible only if the alloys could be cast in an open atmosphere using conventional casting techniques. This paper describes a method for casting binary and ternary aluminum-3% lithium ingots. The alloys were cast using conventional techniques in an open atmosphere under salt flux. The melting procedure and casting technique are highlighted and the intricate characteristics of the castings are discussed. The mechanical properties of the heat treated and aged castings are also examined so as to provide a basis for understanding the quality of the cast ingots.     

铝锂合金T型自冲铆接头疲劳特性及失效机理

为研究T型自冲铆接头的疲劳特性,以铝锂合金(AL1420)同种及其与铜合金(H62)和不锈钢(410)异种组合制备的AA、HA和SA三组T型自冲铆接头为研究对象,基于其静力学试验采用正弦波进行拉-拉加载疲劳试验,用二参数威布尔分布对所得疲劳数据的有效性进行验证,采用最小二乘拟合直线得到拟合的F-N曲线,并采用SEM扫描电镜对各组典型疲劳失效断口进行微观分析。结果表明:SA组疲劳寿命对载荷变化最敏感,并且疲劳寿命随相对滑移量的增加而减小;由三组T型接头失效形式可看出接头薄弱环节有由铆钉向板材转移的趋势;从微观分析疲劳断口可知裂纹萌生区多为形貌特征较为平坦的准解理,裂纹瞬断区形貌更加突出,多为沿晶断裂或韧窝形貌。     

Nd:YAG激光焊接对铝锂合金组织和织构的影响

采用Nd:YAG激光进行了5A90铝锂合金薄板的对焊实验,借助光学显微镜、扫描电镜及EDS能谱、背散射衍射技术测试了焊缝的显微组织、合金元素分布及焊缝中的微观织构,并与母材进行了比较。结果表明:Nd:YAG激光焊接使5A90铝锂合金的微观组织和微观织构发生了很大的变化。焊缝区呈现出大量的等轴枝晶组织,这是由于焊缝中存在较多的异质形核点和较高的成分过冷度。焊缝中织构呈随机分布的状态,激光焊接完全改变了母材面心立方金属的冷轧织构组织。     

LOW CYCLE FATIGUE BEHAVIOR OF TWO Al-Li ALLOYS

Abstract—The low cycle fatigue (LCF) behavior of two aluminum-lithium alloys was investigated. Efforts were aimed at understanding the effects of microstructure on the cyclic stress-strain behavior and methods by which different microstructures accommodate plastic strain. These goals were achieved by analyzing the cyclic response and the deformed microstructure of each alloy. Direct-chill cast and rolled X2095 exhibited immediate cyclic softening followed by a plateau region. Strain was distributed in a homogeneous manner throughout the microstructure. Mechanically alloyed and forged AA5091 (formerly referred to as 905XL) also deformed in a homogeneous manner, but the cyclic response was characterized by initial softening followed by gradual hardening. Over-strain loops were applied during some of the LCF tests, the purpose of which was to simulate the strain history of the material ahead of a growing fatigue crack during a tensile overload. The over-strain response suggested that the intrinsic material response does not contribute to crack retardation in X2095 or AA5091.     

Estimation of the effects of plasticity and resulting crack closure during small fatigue crack growth

On the basis of a plastic-strip model and the method of singular integral equations, a closed-form analytical solution of the problem of an elastic-plastic plate containing a rectilinear fatigue crack is considered. The solution is used for the prediction of fatigue growth of `mechanically-small' crack by accounting for reverse plastic yielding and plasticity-induced crack closure in the material. The main effects of these factors on the crack-growth rate are analyzed, and the predicted results are compared with experimental data on small fatigue-crack growth in a aluminum-lithium alloy 2091-T351 and Fe-3% Si alloy.