Al-Fe合金组织优化及相关机制研究进展

Al-Fe合金以其优异的性能和广阔的应用前景受到科研人员的高度关注。本文综述共晶、过共晶Al-Fe合金的凝固特性，概述外加条件及合金元素对Al-Fe合金微观组织的影响，介绍不同工艺制备方法得到的Al-Fe合金的组织及性能，并对Al-Fe合金应用状况及在汽车、航空方面的应用前景进行描述。最后，对制备高性能Al-Fe合金的核心问题——细化富铁相及提升铁含量进行讨论，并指出合金元素的引入方式与液态环境的精确调控是Al-Fe合金未来的研究重点。     

Medium-range order clusters in metal melts

Structures of molten metals Cu and Al, alloys Cu-Al, Al-Ni, Al-Fe and, Al-Si were investigated by using high temperature X-ray diffractometer. It has been found that there are not only short-range order structures (SRO) but also medium range order structures (MRO) in Cu-Al, Al-Ni, Al-Fe alloy melts. There are only short-range order structures in the pure metals Cu and Al and Al-Si alloy melts at different temperatures. It has also been found that the presence and the disappearance of the MRO structures in molten metals are a function of temperature. Moreover, the pre-peak in the structure factor is an indication of MRO in molten metals. There is a pre-peak in each structure factor S( Q) of Al-Fe alloy melt containing 14 wt% Fe, 16 wt% Fe and 19 wt% Fe at 1550℃, showing that there are the medium range order structures in these alloy melts. For Al-35wt% Ni alloy, the pre-peak exists in S(Q) when the temperature is lower than 1300?, and it is weakened drastically when the temperature surpasses 1300℃. The     

Thermodynamic Stability of the Molding Materials for Casting Ti-6Al-4V Alloy

omoxForitShighstrength-to-weightratio,excellentcorm-sionresisboceandappropriatehightemperatureproPer-ties,Ti-6Al-4VcastingsarewidelyusedasimportantstIUctUralcOrnpoentSforaerospaceaPplications.ButthetuterachonofmoltentitaniurnanoywithmoldingmaterialsmayresultinreducedqUalihesandflexundandfatigUestrengthofthecashngS['J.Thereasoishighchendcalre-activityofmoltentitaniumleadstofowredchedricalsta-bilityofmodingmaterialsincontactandsutheeconed-nationcauseshaIdeningofcasting['1.fomereseareherstr…     

Purification technology of molten aluminum

Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclu-sions from molten aluminum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used to produce pulse gas currents for the rotary impeller degassing method. Water sim-ulation results show that the size of gas bubbles can be decreased by 10%- 20o//oo as compared with the constant gas current mode. By coating ceramic filters or particles with active flux or enamels, composite filters were used to filter the scrap A356 alloy and pure aluminum. Experimental results demonstrate that better filtration efficiency and oper-ation performance can be obtained. Based on numerical calculations, the separation efficiency of inclusions by high frequency magnetic field can be significantly improved by using a hollow cylinder-like separator or utilizing the effects of secondary flow of the melt in a square separator. A multi-stage and multi-media purification platform based on these methods was designed and applied in on-line processing of molten aluminum alloys. Mechanical properties of the processed scrap A356 alloy are greatly improved by the composite purification.     

Structure of Liquid Aluminum and Hydrogen Absorption

The hydrogen content in aluminum melts at different temperature was detected. The structure in aluminum melts was investigated by molecular dynamics simulation. The first peak position of pair correlation function, atomic coordination number and viscosity of aluminum melts were calculated and they changed abnormally in the same temperature range. The mechanism of hydrogen absorption has been discussed. From molecular dynamics calculations, the interdependence between melt structural properties and hydrogen absorption were obtained.     

铁在铝铁合金加工软化中的作用

铝及铝铁合金加工软化行为表明，质量分数为０．９９９６的铝没有加工罗化现象，而在其中加入铁配成Ａｌ－Ｆｅ合金，当轧制率达９０％以上时出现加工软化现象，研究认为，Ａｌ中Ｆｅ的质量分数接近Ａｌ－Ｆｅ相图中共晶成分时，形成ＦｅＡｌ３粒子，起到净化Ａｌ基体作用，化后的Ａｌ基体层错能提高，促使加工软化现象出现。     

Liquid structure of pure iron by X-ray diffraction

The liquid structure of pure iron at 1540, 1560 and 1580℃ was studied by X-ray diffraction. The results show that near the melting point there is a medium-range order structure that fades away with the increasing temperature. The average nearest distance of atoms is almost independent of the melts temperature, but the average coordination number, the atom cluster size and the atom number in an atom cluster all decrease with the increasing temperature of the melt. Near the melting point there are a lot of atom clusters in the pure iron melt. The atom cluster of pure iron has the body-centered cubic lattices, which are kept from the solid state. And the body-centered cubic lattices connect into network by occupying a same edge. The atoms in the surrounding of the atom clusters are arranged disorderly.     

铝合金熔体氢含量计算模型建立及其可信性评价

为了更加深入的了解铝合金凝固特性,经理论分析后,建立了铝液中氢扩散过程的数学模型,对铝合金熔体吸/释氢过程进行了动力学推导.对不同的熔体温度、保温时间以及熔体初始氢含量等工艺参数条件下铝熔体的表面吸氢情况进行了计算,并利用铝合金熔体氢分压动态测氢装置,对实际扩散过程做了测试,给出了诸多因素作用下的熔体氢含量变化曲线.计...     

熔盐电解法制备铝钙合金中的反电动势

研究了在CaCl2-CaF2纯钙盐体系中下沉式铝液槽结构熔盐电解法生产Al-Ca合金新工艺,采用连续脉冲-示波器法测定电解过程的反电动势,研究了在实验室条件下电解温度、电流密度、电解时间和极距对熔盐电解法制取铝钙合金的反电动势的影响.用熔盐电解法并采用铝阴极生产Al-Ca合金比对掺法更加节省电能,降低了Al-Ca合金的生产成本,是一种有经济价值的生产方法,有很好的发展前景.     

Isothermal corrosion Fe3Si alloy in liquid zinc

1. Introduction In continuous hot-dip coating lines, the immersed bath hardware (e.g. bearings, sink, stabilizer, and cor- rector rolls, and also support roll arms and snout tip) is subject to corrosive attack by the molten bath material. In the series of…     

Cu对Al-Fe双金属界面扩散层形貌及其结合强度的作用

本文通过对采用 Al—Cu 液态合金共渗复合铸造方法得到的 Al—Fe 双金属材料的界面扩散层形貌观察和力学性能试验,研究了 Al—Fe 双金属界面扩散层形貌和力学性能随 Al—Cu 合金渗液中 Cu 含量不同的变化规律.     

Influence of hydrogen content on the behavior of grain refinement in hypereutectic aluminum-silicon alloy

Dissolved hydrogen is harmful to mechanical properties of refined hypereutectic aluminum-silicon alloys. In the present work, by using a stepped-form mold and the hydrogen-detecting instrument HYSCAN Ⅱ, the relationship between the initial hydrogen content in the melt and the refinement effect on the casting of hypereutectic aluminum-silicon alloy was investigated. The experimental results show that the cooling rate, the hydrogen content and the grain refinement effect are three interactive factors. When the hydrogen content is above 0.20 mL/100 g and the cooling rate is lower than that in 50 mm-thick step, hydrogen dissolved in the alloy melt influences the grain refinement effect. With increasing the cooling rate, the critical hydrogen content increases too. It is expected that much hydrogen in the melt make the net interfacial energy larger than or equal to zero, resulting in the shielding of the particles AlP during solidification and that the critical gas content is closely related to the critical radius of embryo bubbles.     

STUDY ON THE FORMATION OF DEFECTS IN DURALUMIN FORGINGS

Aluminiumalloys2024,7075arewidelyappliedtothemainsupportingmemberofplane.suchasrib.frame.wingbeam.becauseoftheirexcellentpropertiesofhighspecificstrength.coldandhotformingperformance,aswellasjointing.Akindofdefectnamed"oxidefilm-isoftenfoundinfracturedsurfaceofplaneforgings.whichwillseriouslyimpairthemechanicalpropertiesandfatiguestrengthofduraluminforgings,andgreatlydecreasethequalityoftheproducts.Accordingtothemacroappearanceinthefracturedsurface.thedefectsaredivivedintoseveraltypesf"brightd…     

Addition of Ce as additive to Pb-Ca-Sn-Al grid alloy for lead acid battery

0　ＩＮＴＲＯＤＵＣＴＩＯＮＰｂ Ｃａａｌｌｏｙｃａｎｉｍｐｒｏｖｅｔｈｅｍａｉｎｔｅｎａｎｃｅｆｒｅｅｃａｐａ ｂｉｌｉｔｙｏｆｌｅａｄａｃｉｄｂａｔｔｅｒｙｗｉｔｈｈｉｇｈｈｙｄｒｏｇｅｎｅｖｏｌｕｔｉｏｎｏｖｅｒｐｏｔｅｎｔｉａｌ.ＢｕｔｔｈｅｃａｓｔｉｎｇｐｒｏｐｅｒｔｙｏｆＰｂ Ｃａａｌｌｏｙｉｓｎｏ ｇｏｏｄａｎｄｔｈｅｐａｓｓｉｖａｔｉｏｎｌａｙｅｒｏｆｈｉｇｈｉｍｐｅｄａｎｃｅｆｏｒｍｅｄｄｕｒｉｎｇｔｈｅｏｘｉｄａｔｉｏｎｐｒｏｃｅｓｓｈａｓｓｉｇｎｉｆｉｃａｎｔｉｎｆｌｕ ｅｎｃｅ…     

复合中间合金对铝合金机械性能的影响

以工业纯铝（L2）为基础,添加不同百分含量的合金元素Re、Al-Ti-B与Al-X等,以及选择适当的热处理工艺措施,对其所引起的机械性能、导电性能的变化进行了研究,旨在寻求一种新的复合中间合金材料替代原来各合金元素单独加入,从而获得导电性较好,强度较高的铝合金电脑散热片材料．研究结果表明：当加入的复合中间合金中Re、Al-Ti-B与Al-X比例为1：3：1时,其效果最佳．     

Grain Refining Performance of SHS Al—50TiC Master Alloys for Commercially pure Aluminum

An Al-50wt^TiC composite was directly synthesized by self-propagating high-temperature synthesis(SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminun.The microstructure and grain refining performance of the synthesized master alloy were emphatically investigated.The SHS master alloy only ocntained submicron TiC particles except for Al matrix.Moreover,TiC particles were relatively free of agglomeration.Grain refining tests show that adding only 0.1wt^ of the master alloys to the aluminum melt could transform the sturcture of the solidified samples from coarse columnar grains to fine almost 1.5h at 1003K.Therefore,it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys,and that it is highly resistant to the grain refining fading encountered with most grain refiners.     

双辊铸轧超高强铝合金有限元数值模拟

采用有限元法对双辊铸轧7075和7050铝合金的工艺过程进行了数值模拟,研究了合金成分和铸轧速度对铸轧熔池内温度场、流场和凝固场的影响规律。结果表明,在同一铸轧速度条件下,随着合金的等效比热增大,合金在铸轧熔池内的温度梯度随之减小,凝固速率减慢;对于同一种合金,随着铸轧速度增加,合金的速度梯度随之增大,熔池内所形成漩涡的位置下降。模拟结果为下一步的铸轧实验提供了理论依据     

用高低温熔体混合法制备Al- 18%Si合金

采用熔体混合法将不同温度的纯铝熔体与600 ℃半固态Al-36%Si合金熔体混合制备Al-18%Si合金,研究纯铝液温度、保温温度和保温时间对Al-18%Si合金初生硅相显微组织及力学性能的影响。实验结果表明:熔体混合法可制得初生硅为颗粒状且均匀分布的Al-18%Si合金;在一定范围内,初生硅的粒径随熔体温差的增大而减小,随保温时间的延长呈先减小后长大的趋势;900 ℃的铝液与600 ℃半固态Al-36%Si合金熔体混合后于750 ℃保温20 min获得的Al-18%Si合金力学性能最好,初生硅平均粒径最小。     

乙酰胺-尿素-NaBr熔体中电沉积Tb-Mg-Ni合金的研究

在353?K的乙酰胺-尿素 NaBr熔体中，Ni（Ⅱ）一步不可逆还原为金属Ni,测得在Pt电极上α为0.21和D0为1.15×10-8?cm2•s-1；Cu电极上α为0.18和D0为1.44×10-6?cm2•s-1.Tb（Ⅲ）和Mg（Ⅱ）不能单独还原为Tb和Mg，但是可以被Ni（Ⅱ）诱导共沉积.由恒电位电解法得到非晶态的Tb Mg Ni 合金膜.合金中Tb的含量随着阴极电势的负移先增大而后减小，随Tb（Ⅲ）/ Ni（Ⅱ）摩尔比增大而增大，Tb的最大含量可达87.88%；Mg的含量随着阴极电势的负移而增大，最大可达12.78%，在Tb（Ⅲ）/Ni（Ⅱ））摩尔比为3.4/1，Mg（Ⅱ）/Ni（Ⅱ）摩尔比为8/1时，Mg/Ni原子比为2/1，符合Mg2Ni储氢合金的组成.     

铝电解阴极过程的电化学研究

用电化学方法研究了在纯冰晶石、工业电解质和低熔点电解质中铝的电解沉积和溶解损失研究表明，铝的沉积为简单的3电子传递反应；铝的再溶解损失由金属／熔液界面层中的稳态传质控制，其速度分别为0．247，0102和0．0423A·cm－2结果证明在低熔点电解质熔液中，电解制取铝具有很高的电流效率．