As-cast microstructure of Al-Zn-Mg and Al-Zn-Mg-Cu alloys added erbium

1 INTRODUCTIONMany researches show that the properties ofaluminum and its alloys can be remarkablyi mproved withreasonable rare earth additions .Theactions of rare earth elements in the aluminumalloys consist in alterant-agent , micro-alloying andso on[1 3].By far element scandiumis the most ef-fective rare earth element which i mproves thealuminum alloys properties[4 6]. However , theprice of scandiumis very high.Therefore ,it s veryessential to find a new rare earth element , whichacts …     

Microalloying Al alloys with Sc:a review

As a kind of important light alloys,the Al alloys exhibit mechanical properties that are closely related to the microstructures.Changing the main alloying elements and adjusting heat treatments are usually approaches to tune the microstructure and hence artificially control the mechanical properties.However,the windows for the two approaches have become quite narrow,after extensive studies in the last half of century.Microalloying has become the most promising strategy to further modify the microstructure and improve the mechanical properties of Al alloys,among which the element of scandium(Sc) is especially powerful.In this paper,the recent progresses in Al alloys microalloyed with Sc are briefly reviewed,focusing on the microstructural characterization,strengthening response,and underlying mechanisms.The possible key research points are also proposed for the further development of Al alloys microalloyed with Sc and other rare earth elements.     

铝合金细化相Al3(Zr,Sc)的能量和弹性性质的第一性原理研究

微合金化是强化铝合金的重要手段,Sc作为铝合金有效的细化剂而引起广泛关注。实验研究表明,在铝基体中同时添加Zr和Sc,在铝基质中形成Al3(Zr,Sc)细化相,可以实现更好的晶粒细化。本文基于密度泛函理论的第一性原理方法,系统地研究了不同Sc/Zr配比下形成的Al3(Zr,Sc)细化相的能量和弹性性质。结果表明,当Sc/Zr不高于1/3时,Al3(Zr,Sc)相具有较大的形成焓绝对值,细化相将优先于Al3(Zr,Sc)相析出。同时,Sc元素的加入有利于界面的形成,提高界面的结合强度和润湿效果,但高于1/3的Sc/Zr比对界面性能的提高并无积极作用。并且,Zr的加入可以有效提高细化相的弹性性能,并削弱Al3Sc的弹性各向异性特征。此理论研究指出,微合金化Zr和Sc的共同添加时Sc/Zr不高于1/3时,可以保证细化效果并大大降低合金的成本。     

Study on the Microstructure and Wettability of an Al-Cu-Si Braze Containing Small Amounts of Rare Earth Erbium

The effect of adding small amounts of rare earth Er on the microstructure of an Al-Cu-Si braze alloy has been investigated. Several Al-20Cu-7Si braze alloys containing various contents of Er were prepared, and their melting temperature, microstructure, hardness, and wettability in contact with 3003 aluminum alloy substrates were determined. The results indicate that the constituents of the microstructure of Al-20Cu-7Si-Er braze alloys are similar to those in the Al-20Cu-7Si alloy, and comprise of solid solutions of aluminum, silicon, and the intermetallic compound CuAl₂. When the Er content increases, the size of the Al phase decreases, and the needle-like Si phase is thickened, and transformed to a blocky shape. Moreover, small amounts of Er can improve the wettability and hardness of the Al-20Cu-7Si braze alloy; however, the melting temperature of the Al-20Cu-7Si alloy does not change.     

Nano-composite Powder of Tungsten Coated Copper Produced by Thermo-chemistry Co-reduction

对Al-Mg-Mn-Zr-Er合金进行TIG焊接,研究了母材和焊缝的微观组织特征,重点研究了Er在焊缝中的存在形式及其对焊缝微观组织的影响.结果表明:Er在焊缝中以Al3Er相的形式存在,其中初生Al3Er具有细化晶粒的作用,次生Al3Er具有弥散强化的作用;在熔合线附近出现由细小等轴晶组成的细晶区,该区域的出现与Er元素的添加有关.     

铒微合金化铝合金的研究进展

微合金化是提高铝合金性能的重要途径,控制微量元素的种类和含量,充分发挥微量元素的作用是当前铝合金研究的主要方向之一。大量研究表明:廉价的Er能够起到有效的微合金化作用,Er元素在铝合金中可形成纳米级Al3Er强化相,并可通过与Zr复合作用形成Al3(ZrxEr1-x)复合相,比Al3Sc相具有更好的热稳定性,从而可以改善铝合金组织,大幅度提高铝合金的强度或塑性、明显抑制铝合金的再结晶以提高其耐热性,改善其综合性能。本文作者针对微合金化元素Er在铝合金中析出Al3Er相及Al3(ZrxEr1-x)复合相的过程及其对合金组织和性能的影响机理,以及Er微合金化在几类工业合金体系中的作用,介绍含铒铝合金的最新研究进展。     

Effects of erbium on microstructure and mechanical properties of as-cast Mg-7Zn-3Al alloy

Mg-7Zn-3Al-xEr(x=0.1,0.4,0.7) magnesium alloys were prepared by permanent mould casting.The effects of rare earth element of erbium on the microstructure and mechanical properties of as-cast Mg-7Zn-3Al alloy at both room temperature and elevated temperatures were investigated with optical microscopy,scanning electron microscopy/energy dispersive X-ray spectroscopy,differential scanning calorimetry,and tensile testing.The results show that the quasi-continuous grain boundary networkedτ(Mg_(32)(Al,Zn)_(49)...     

Al-Zn-Mg-Cu-Li-Er合金时效组织中Er相的TEM观察

采用TEM对56％Zn，1．9％Mg，1．6％Cu，1.0％Li，0．3％Er(质量分数)合金中的Er相进行研究．发现Er在合金中主要以Al3Er形式存在．Al3Er在合金中的形状为块状、点状、片状或蠕虫状，部分Al3Er与铝合金基体共格，细小的Al3Er可作为η相异质形核的核心。Er在台金的晶界有很大的偏析，而且晶界处Al3Er的存在，使该处晶界析出物不连续。     

On the modification of hypereutectic Al-Si alloys using rare earth Er

Hypereutectic Al-17.5Si (wt pct) and Al-25Si (wt pct) alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hypereutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as friction and wear tests. It was found that optimal amount of Er exists in modifying the hypereutectic Al-Si alloys. An appropriate addition of Er improved the anti-wear properties, and reduced the friction coefficient of the hypereutectic Al-Si alloys studied. The primary silicon crystals in the hypereutectic Al-Si alloys were refined with the suitable addition of Er element. The modification mechanism was also discussed in this paper.     

均匀化处理对挤压态Al-4Si(-0.2Er)合金显微组织及性能的影响

为改变Al-Si合金中第二相的尺寸、形貌及分布,改善合金的电学和力学性能,选用稀土元素Er作为合金化元素,制备了Al-4Si、Al-4Si-0.2Er合金,探究了稀土Er及均匀化处理对挤压态Al-4Si、Al-4Si-0.2Er合金显微组织及电学、力学性能的影响。结果表明:稀土Er有利于促进固溶态Si的析出且形成新相ErSi₂,增加了合金中第二相数量,弥散强化效果明显,提高了合金的力学性能,且导电率保持稳定。均匀化处理工艺为540 ℃×1 h炉冷的Al-4Si-0.2Er合金综合性能较强,均匀化处理促进了第二相的析出,同时减小了第二相尺寸,使其以颗粒状弥散分布,Al-4Si-0.2Er合金的导电率由挤压态的51.61%IACS提高至56.44%IACS,提高了9.4%,炉冷过程导致了合金的力学性能略有下降,抗拉强度为87.80 MPa,伸长率为35.9%,硬度为36.00 HV0.3。     

Investigation on Behavior of Rare Earth Element Cerium in Aluminum-Lithium Alloys by Internal Friction Method

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Effect of impurities of Fe and Si on the structure and strengthening upon annealing of the Al–0.2% Zr–0.1% Sc alloys with and without Y additive

The effect of impurities of Fe and Si on the microstructure and kinetics of the change in the hardness during annealing of the cast Al–0.2% Zr–0.1% Sc and Al–0.2% Zr–0.1% Sc–0.2% Y alloys has been studied. It has been found that the presence of the impurities of Fe and Si in the Al–0.2% Zr–0.1% Sc alloy leads to a partial binding of scandium into the (Al, Fe, Si, Sc) and (Al, Fe, Sc) phases of crystallization origin and to the corresponding depletion of the aluminum solid solution of Sc. It has been shown that as a result, the strengthening is significantly decreases upon annealing. The addition of 0.2% Y into the Al–0.2% Zr–0.1% Sc alloy with impurities of Fe and Si leads to the formation of the Al₃Y and (Al, Y, Fe, Si) phases, whereas Sc is completely dissolved in the aluminum solid solution. It has been shown that the addition of Y leads to an increase in the thermal stability of the alloys during annealing at temperatures of 250, 300, and 370°C and eliminates the negative effect of impurities of Fe and Si.     

Optimal modifying and refining processes for A356 aluminium alloys

M illions of alum inium alloy com ponents are produced using A356 alum inium alloys, which provide high fluidity, good 'castability'and m echanical properties. A356 alloys are widely used to fabricate structural castings for autom otive and other industrial applications. For α (Al) refining,A356 alum inium alloys usually apply Al-Tim aster alloys in the range 0.08-0.20% Ti, resulting in high consum ption of Al-Ti m aster alloys and higher production cost.M odification ofthe Al-Sieutectic …     

稀土元素对铝合金组织与性能影响的研究进展

稀土元素因为其有效、稳定的变质作用,被广泛应用于多种金属材料中。变质处理可以细化合金组织,从而提高合金的力学性能,不同的稀土元素对铝合金的变质效果不同。重点介绍了几种常用稀土元素对铝合金显微组织、力学性能的影响及其变质机理,综述了现阶段国内外稀土铝合金的研究现状,并阐述目前存在的问题,以及对未来研究进行了展望。     

微量稀土元素Er对1420合金织构的影响

采用X射线衍射分析、金相组织观察和透射电镜等技术手段,研究了Er对1420合金板材织构的影响。结果表明,微量Er能够增强1420合金板材变形织构,其中黄铜织构B{011}〈211〉增强最为明显,其主要原因是加入微量Er可降低1420合金的层错能,同时Er与位错之间存在较高的交互作用能。另外,Er的抑制再结晶和细化再结晶晶粒作用也有利于变形织构的形成与维持。     

稀土元素在铝合金阳极氧化及其后处理工序中的应用

在铝合金阳极化溶液中加入稀土添加剂,能够提高氧化膜的耐蚀性能;将稀土盐用于铝合金氧化膜的封闭处理,效果也比较理想,因而稀土元素在铝合金表面处理领域中具有良好的应用前景。介绍了国内外善于稀土元素在铝合金阳极氧化及其后处理工序中的应用情况,并结合目前的研究现状,提出了今后研究中需要进一步探讨的问题。     

含铒铝合金显微组织对疲劳裂纹扩展的影响

对含铒铝合金板材进行了不同的热处理,分析了各板材的显微组织对疲劳裂纹扩展和力学性能的影响。结果表明:晶粒的长/径比越小,板材的疲劳裂纹扩展速率越慢;且随着疲劳裂纹扩展速率的降低,裂纹宽度增加且裂纹路径曲折;稀土元素Er的加入,在合金中形成Al_3(Er,Zr)第二相粒子,其强烈地钉扎位错,阻碍位错运动,以减少位错在晶界处的聚集产生的应力集中,降低板材的疲劳裂纹扩展速率。     

铒对工业纯铝显微组织和性能的影响

采用扫描电子显微镜、能谱仪、万能材料试验机等仪器,研究了稀土元素铒Er对工业纯铝显微组织和性能的影响。结果表明,在铸态组织中,除少量Er过饱和固溶于α-Al,其余以第二相的形式存在于晶界处。析出在晶界处的第二相存在两种形态:颗粒状和长条状。颗粒状的AlFeSiEr第二相含有较多的Er,长条状的AlFeSiEr第二相中的Er含量较少。在拉拔态组织中,Al-Er合金中的第二相多以颗粒状形式存在,而工业纯铝中的第二相还存在短棒状的第二相。对工业纯铝进行Er微合金化后,提高了硬铝导线的耐热性。其耐热性的提高是固溶Er阻碍位错和亚晶界迁移所致。     

Differences of grain-refining effect of Sc and Ti additions in aluminum by empirical electron theory analysis

The differences of grain-refining effect between Sc and Ti additions in aluminum,which cannot be substantially explained by traditional theories,were carefully studied.The empirical electron theory(EET) of solids and molecules was employed to calculate the valence electron structures(VES) of Al3Ti and Al3Sc.The conclusions can be drawn that,in the two alloys Al-Ti and Al-Sc,the different valence electron structures of Al3Ti and Al3Sc and the consequent differences of growth habit of the two particles,and th...     

Effect of Cerium and Yttrium on Aging Processes in Alloys of the Al – Mg System

The effect of small additives of rare earth metals (REM) (cerium and yttrium in an amount of about 0.6 wt.% each) on the decomposition of supersaturated solid solution of magnesium in aluminum in Al – Mg alloys bearing up to 16.6% Mg is studied in the process of natural and artificial aging. It is shown that the addition of REM delays the decomposition of the aluminum solid solution.