镁锂合金首次用于高轨卫星

<正>前日发射成功的通信技术试验卫星三号在预埋件、支架和部分机箱壳等部位应用了西安四方超轻材料有限公司自主研发的镁锂合金材料,使整个卫星减重约173kg,大大提高了卫星的有效载荷量。这是我国首次在高轨卫星上应用镁锂合金材料。本次应用的镁锂合金LA103Z及LA43M代表了我国镁锂合金发展的技术前沿,被称为未来最为"绿色环保"的革命性材料。     

论镁锂合金特殊性及其熔铸加工工艺

作为集高比强度与高比弹性模量为一体的超轻合金材料,镁锂合金具有良好的减振性能与可焊性,成为我国材料研究学界的关注焦点。本研究主要通过解析镁锂合金的晶体结构及特殊性,说明镁锂合金熔铸加工工艺。     

郑州轻研成功研制0.014 mm超轻镁锂合金箔材

正近日,郑州轻研合金科技有限公司通过优化镁锂合金成分设计,控制镁锂合金的密度并改善其加工性能,采用卷式法研制出厚度仅为0.014 mm的超轻镁锂合金箔材,而且已经成功通过国内权威声学厂家的声学测试、可靠性测试以及初步量产测试,为镁锂合金箔材的推广打下了坚定的基础。超轻镁锂合金箔材凭借其基材自身优异的导     

陕西研制出目前最轻金属结构材料

<正>2月21日,从陕西省镁锂合金工程研究中心获悉,该中心研制出新型镁锂合金,其密度根据用途可达到0.96~1.64 g/cm~3,是目前世界上最轻的金属结构材料。2016年12月22日,我国成功发射的首颗全球二氧化碳监测科学实验卫星(简称"碳卫星")中的高分辨率微纳卫星上,几乎整颗应用了陕西省自主研制生产的这种超轻材料。     

0.014mm超轻镁锂合金箔材研制成功

正日前,郑州轻研合金科技有限公司采用卷式法成功制备出厚度仅为0.014mm的超轻镁锂合金箔卷材,这也是国内乃至世界上首次制备出这么薄的镁合金箔材。目前,郑州轻研合金科技有限公司通过优化镁锂合金成分设计、控制镁锂合金的密     

镁锂合金的重点专利分析及发展建议

本文选取了国内外镁锂合金的重点专利,运用专利信息分析方法,深入分析镁锂合金的核心技术、竞争对手的专利布局情况,帮助我国相关研制单位梳理镁锂合金重点专利中的技术路线及发展趋势,转化吸收重点专利技术中的研发思路,加快镁锂合金技术研发的创新,逐渐降低镁锂合金的研制、生产成本,拓展镁锂合金的产业应用。     

含Cu镁锂合金组织与性能调控研究进展

镁锂合金具有超低密度、极高的比强度与比刚度、优异的电磁屏蔽性能及阻尼性能,目前广泛应用于追求轻量化的航空航天、新能源汽车、电子产品、生物医疗等领域。由于合金元素镁和锂均为活泼金属,在服役过程中镁锂合金会存在多种形式的腐蚀过程,同时二元镁锂合金强度较低,以上两点严重制约了其广泛应用。耐蚀涂层可以有效提高镁锂合金的腐蚀抗力,含铜镀层被证实能够提升镁锂合金耐蚀性。改善镁锂合金强度的工艺主要有合金化、热处理、加工变形等,其中合金化是最基本的强化手段。Cu合金化可以对镁锂合金中的组织与性能进行调控,改善镁锂合金的强度。本文对含Cu镁锂合金的研究进展及其应用情况进行综述,总结了目前含Cu镁锂合金耐蚀与力学性能的相关研究成果,重点梳理了铜元素在镁锂合金中的作用,为含Cu镁锂合金的实际应用提供一定的理论指导。     

开发江西锂资源大有可为

锂，被称之为“能源金属”，广泛应用于工业部门和高新技术产业，如：碳酸锂用作铝电解添加剂，可以提高电流效率1％～3％，降低电耗400kw·h／t产品左右；锂电池作为一种高效储能电池，已实现工业化生产，二次锂电池作为电动汽车的动力电源，已进入实用化阶段；溴化锂用于中央空调和致冷设备，可以节电40％以上；锂一铝合金因具有很高的比强度、良好的耐蚀性和可焊性等优点，已在航空和航天工业中获得应用，成为重要的结构材料；镁─锂合金被称为浮在水面上的超轻合金，因其比重小，冷加工性能好，在宇航、手提电子设备上具有广阔实用前景…     

国外动态

国外动态废铝除镁与除锂的最新工艺镁是铝合金的一种常用合金元素，全世界生产的原镁约有５０％用于制造铝合金；铝－锂合金具有密度低、弹性模量高、比强度大等特点，是一种新型的航空航天材料以及其他轻型结构材料，已获得日益广泛的应用。但为了提高再生铝的价值与扩大...     

陕西研制出世界最轻金属结构材料

正近日,陕西省镁锂合金工程研究中心研制出一种新型镁锂合金材料,其密度根据用途可达每立方厘米0.96~1.64g之间,是目前世界上最轻的金属结构材料。所研制的镁锂合金与铝合金相比,同样大小,重量仅是铝合金的一半,但比强度高于铝合金。此外,这种新型镁锂合金的阻尼性能优异,是铝合金的十几倍,减震降噪效果好,在屏蔽电磁干扰方面表现突出。     

Al–Cu–Li and Al–Mg–Li alloys: Phase composition,texture, and anisotropy of mechanical properties (Review)

The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al–Cu–Li and Al–Mg–Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S₁ (Al₂MgLi), T₁ (Al₂CuLi), and δ' (Al₃Li) phases. The fraction of the δ' phase in Al–Cu–Li alloys is shown to be significantly higher than in Al–Mg–Li alloys. Therefore, the role of the T₁ phase in the hardening of Al–Cu–Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al–Cu–Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al–Cu–Li and Al–Mg–Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.     

On stress corrosion cracking in aluminum-lithium alloys

The stress corrosion cracking (SCC) susceptibility of two aluminum-lithium alloys, a binary AlLi and a ternary AlLiCu alloy, in 0.5 M NaCl solution was investigated using the constant elongation rate technique (CERT). Susceptibility increased with decreasing strain rate and with aging. The alloys were susceptible under both anodic and cathodic applied potentials. The susceptibility dependence of the alloys as a function of applied potential correlates well with published hydrogen permeability data. The susceptibility increased dramatically when hydrogen was charged into the specimen using a hydrogen re-combination “poison” during CERT testing. These experiments suggest that hydrogen plays a major role in the SCC of these alloys. A brittle hydride having the composition LiAlH₄ forms in the AlLi system under conditions of severe SCC susceptibility. The brittleness of the hydride is explained. The formation of the hydride is a sufficient condition for SCC of AlLi alloys. A process of SCC in AlLi alloys is proposed wherein hydrogen causes damage by the formation of a hydride.     

Effect of Impurities and Cerium on Stress Concentration Sensitivity of Al-Li Based Alloys

Ｔｈｅｒｅａｒｅａｌｗａｙｓｓｏｍｅｇｅｏｍｅｔｒｉｃａｌｄｉｓｃｏｎ ｔｉｎｕｉｔｉｅｓ ,ｓｕｃｈａｓｆａｓｔｅｎｅｒｈｏｌｅｓ ,ｆｉｌｌｅｔｓａｎｄｇｒａｖｅｓ ,ｉｎｐｒａｃｔｉｃａｌａｉｒｃｒａｆｔｃｏｎｓｔｒｕｃｔｉｏｎｃｏｍ ｐｏｎｅｎｔｓ .Ｉｎｔｈｅｖｉｅｗｏｆｍａｔｅｒｉａｌｍｅｃｈａｎｉｃｓ ,ｔｈｅｓｅｇｅｏｍｅｔｒｉｃａｌｄｉｓｃｏｎｔｉｎｕｉｔｉｅｓｃａｎｂｅｃｏｎ ｓｉｄｅｒｅｄａｓｎｏｔｃｈｅｓ .Ｓｔｒｅｓｓｃｏｎｃｅｎｔｒａｔｉｏｎｕｓｕａｌ ｌｙｏｃｃｕｒｓａｔｎｏｔｃｈ…     

Rapidly solidified P/M X2020 aluminum alloys

X2020 aluminum alloys were produced with variations in the Li/Cu ratio by the ultrasonic gas atomization process. In alloy 68 (Al-4.9Cu-l.2Li) and 69 (Al-4.4Cu-l.55Li) alloys, the Θ′ and T₁, phases are dominant with evidence of the T_B phase. In the 70 (Al-3.5Cu-2.8Li) alloy, the δ′ phase is dominant with a trace of T₁. It was found that Θ′ andT ₁ are effective strengtheners whereas δ′ provides excellent fatigue crack initiation resistance. Overall results indicate that the fracture behavior of three RS-PM X2020 alloys is closely related to alloy production route as well as to the phases present in the alloys. Formerly Research Assistant, Massachusetts Institute of Technology.     

The effect of processing and microstructure development on the slip and fracture behavior of the 2.1 wt pct Li AF/C-489 and 1.8 wt pct Li AF/C-458 Al-Li-Cu-X alloys

Although Al-Li-Cu alloys showed initial promise as lightweight structural materials, implementation into primary aerospace applications has been hindered due in part to their characteristic anisotropic mechanical and fracture behaviors. The Air Force recently developed two isotropic Al-Li-Cu-X alloys with 2.1 wt pct Li and 1.8 wt pct Li designated AF/C-489 and AF/C-458, respectively. The elongation at peak strength was less than the required 5 pct for the 2.1 wt pct Li variant but greater than 10 pct for the 1.8 wt pct Li alloy. The objectives of our investigations were to first identify the mechanisms for the large difference in ductility between the AF/C-489 and AF/C-458 alloys and then to develop an aging schedule to optimize the microstructure for high ductility and strength levels. Duplex and triple aging practices were designed to minimize grain boundary precipitation while encouraging matrix precipitation of the T₁ (Al₂CuLi) strengthening phase. Certain duplex aged conditions for the AF/C-489 alloy showed significant increases in ductility by as much as 85 pct with a small decrease of only 6.5 and 2.5 pct in yield and ultimate tensile strength, respectively. However, no significant variations were found through either duplex or triple aging practices for the AF/C-458 alloys, thus, indicating a very large processing window. Grain size and δ′ (Al₃Li) volume fraction were determined to be the major cause for the differences in the mechanical properties of the two alloys.     

The influence of Li on the nucleation of defects of quenched AlLi alloys

The nucleation and kinetics of defects formed by quenching in two AlLi alloys having Li content of 1.7 and 3.74 at.%Li have been studied by positron annihilation spectroscopy. It has been found that the defect formation is sensitive to the aging time at the temperature from which the samples are quenched. This fact has been related to the Li loss experienced by the alloys aged at high temperature. The quenched-in defects have been identified as vacancy-Li clusters and dislocation loops. The latter are formed by the collapse of the Li-rich vacancy complexes and are very sensitive to the Li content; as a consequence, the loops are decorated by Li-rich zones and are revealed as very effective positron traps in comparison to the vacancy-Li complexes, giving rise to an enhanced trapping.     

Thermodynamic studies and the phase diagram of the Li-Mg system

By means of the electromotive force (emf) method of concentration cells of the following scheme: Li (1) / LiCl-LiF (eut) or LiCi-KCl (eut) / Li-Mg (1) or Li (1) / LiCl-LiF (eut) / Li-Mg (s) Li activities for liquid and solid alloys at the (Mg), (Li), and (Mg) + (Li) two-phase region of the Li-Mg system were determined. Liquid alloys were examined at temperatures from 638 to 889 K at various Li concentrations. The (Mg) solid solutions were investigated in two series: at constant temperatures between 773 and 876 K, with varying Li content, and at fixed Li concentrations, equal to 0.125 and 0.160 molar fractions, at different temperatures between 772 and 849 K. At the two-phase region, (Mg) + (Li), emf measurements were performed in the temperature range 773 to 838 K, with fixed Li concentrations equal to 0.20, 0.25, and 0.275 molar fractions. For (Li) solid alloys, experiments were done at temperatures 773 to 849 K for several constant Li concentrations, between 0.30 to 0.45 molar fractions, respectively. Studies on solid alloys enabled us also to determine the boundaries (Li)/[(Mg) + (Li)] and (Mg)/[(Mg) + (Li)] at temperatures 773 to 831 K. The resulting thermodynamic and phase boundary data of this study were used with other selected references for a critical assessment of the Li-Mg system. The Lukas BINGSS optimization program and BINFKT for the calculation of the thermodynamic functions and of the phase diagram were used. The calculated equilibrium phase diagram at temperatures below 750 K indicates a slightly lower solid solubility of Mg in (Li) in comparison with results from thermal analysis and the recently published Saunders evaluation.     

Grain boundary precipitate free zones in Al-Li alloys

The growth kinetics of δ′ (Al₃Li) precipitate free zones (PFZ) at the grain boundaries has been investigated in several Al-Li alloys at selected aging temperatures ranging from 168 to 225°C and aging times. The PFZs form by a solute depletion mechanism and the PFZ growth can be described as a diffusion controlled process. The activation energy for PFZ growth has been evaluated as 144 kj/mol, which agrees with the activation energy evaluated for the diffusion of Li in α-Al. The PFZ growth has been analyzed on the basis of a diffusion model with due consideration of δ (AlLi) formation at the grain boundaries. With increase in Li content in the alloys, the growth rate of PFZ increases. This observation is explained by a possible increase in the interdiffusion coefficient with the alloy composition. The effect of grain morphology on the PFZs has been studied by comparing the PFZs in recrystallized and unrecrystallized Al-Li alloys.     

Mg_(10)Al_((7-x))Li_2Ti_x(x=0,1,2,3)合金的制备及储氢性能研究

在氩气保护下,采用机械合金化法制备Mg_(10)Al_((7-x))Li_2Ti_x(x=0,1,2,3)合金,并通过XRD、SEM以及DSC等手段对合金进行表征。结果表明,适量的Ti替代Al可以提高合金的吸氢量、降低合金的初始氢化/脱氢温度和提高合金氢化/脱氢动力学性能。Mg_(10)Al_((7-x))Li_2Ti_x(x=1,2,3)合金样品比Mg10Al7Li2合金的初始氢化温度都降低了62K,而初始脱氢温度则分别降低了77、98和59K。当Ti的替代量为x=2时,合金的综合储氢性能最好。     

Microstructure-property relationships in low-density Al-Li-Mg alloys

The present article describes an investigation of the microstructure and tensile properties of cast Al-Li-Mg alloys with very low densities, in the range 2.3 to 2.4 Mg/m³. Low density is achieved by adding Li and Mg in excess of the solubility limit, which prevents subsequent dissolution of the Al₂LiMg particles that form during solidification. A simple model developed during the course of this research allows prediction of the volume fraction of Al₂LiMg and alloy density from alloy composition. The model was used to select two alloy compositions for detailed investigation: A112Li6Mg and A116Li8Mg. The microstructures of the cast alloys consist of coarse Al₂LiMg particles embedded in an Al matrix containing Al₃Li particles. Both alloys exhibit low tensile elongation in the as-cast condition. Additional processing steps were used to modify the microstructural characteristics thought to be responsible for the low tensile elongation of the ascast alloys. The A116Li8Mg alloy, with an Al₂LiMg volume fraction of 0.25, does not exhibit increased tensile elongation as a result of processing, and the brittle nature of this material is attributed to the high volume fraction of the Al₂LiMg phase. The A112Li6Mg alloy, with an Al₂LiMg volume fraction of 0.13, exhibits a remarkable increase in tensile elongation after extrusion, an effect attributed to fragmentation and dispersal of a three-dimensional (3-D) network of the intermetallic phase in the as-cast alloy.