铝钪中间合金的制备方法

本文系统地介绍了目前制取铝钪中间合金的几种方法,对对掺法、熔盐电解法及金属热还原法的优缺点进行了比较,指出作者新近实验成功的氯化钪铝镁热还原法为制备钪中间合金提供了有广阔发展前景的途径。     

铝-钪(2%)合金的制备

传统的生产铝钪合金的方法，成本高，条件复杂，不利于工业生产，我们对金属热还原制取A1—Sc合金进行了研究，简化了生产条件，降低了对原料的要求，缩短了工艺流程，降低了生产铝钪合金的成本，开拓了铝钪合金的应用市场。     

钾冰晶石—氧化钪体系中铝热还原反应过程的研究

在钾冰晶石—氧化钪熔盐中,采用铝热还原和直接电解制备铝钪合金。在引入Al3Sc相生成自由能并考虑活度后,热力学计算表明,铝热还原氧化钪反应在本试验条件下可以发生。750℃在K3AlF6-2%Sc2O3(CR=1.22)熔盐中,电解制备的合金中钪含量可达0.97%,而铝热还原反应所获合金中钪含量小于0.18%,且随反应时间的延长和熔盐中氧化钪浓度的增加,合金钪含量的增幅趋缓。电解合金中钪分布均匀,而铝热还原合金中钪主要存在于边缘区域。     

铝钪合金的现状与展望

概述了钪对铝合金性能的影响,并对铝钪合金发展的历史和现状进行了概括。论述了铝钪合金的制备方法及铝钪合金的性质,如高强度、热稳定性高,焊接性、耐腐蚀性优良等。介绍了几种常用的铝钪合金,评述了铝钪合金的发展前景并指出了我国铝钪合金的研究方向。     

电铝热法冶炼钨铁实验研究

实验以金属热还原法为主，吸收电碳热法的特点，提出了一种工艺流程短，简单适用的电铝热冶炼钨铁合金的方法。     

真空铝热还原法制取金属钙钡锶

阐述了真空铝热还原法制取金属钙、钡及锶的工艺流程 ,并借ⅡA族元素间化学性质相近 ,制取工艺相似的特点 ,成功地取得了在硅铁制镁装置上用铝热还原法制取金属钙的工艺技术条件 ,解决了热力学上高难度还原过程 ,为其他元素的铝热还原法制取提供参考     

铝热还原法制备稀土－铝合金

铝热还原法制备稀土－铝合金张淑芬，李平，杜富英，路连清（中国科学院长春应用化学研究所长春１３００２２）稀土在铝和铝合金中的应用相当广泛。目前流行的方法是在铝电解槽中添加稀上化合物，直接生产稀土－铝合金的方法，对铝厂来说，是合理和方便的。然而，对铝加工...     

硅热还原三硫化二铈制备单硫化铈

研究了硅热还原三硫化二铈制备单硫化铈的新方法。理论计算确定了反应的热力学条件，试验确定了反应温度、时间和还原剂硅过量值等反应条件。分析了反应过程的动力学影响因素并提出了二次反应法减少单硫化铈产物中杂相三硫化二铈的方法，研究了单硫化铈中残留的还原剂硅的分离净化方法。与文献报道的其它方法比较，结果表明：与铝热还原法和碳热还原法相比，硅热还原法制备的单硫化铈纯度高——杂相三硫化二铈低，残留的硅容易分离。与稀土金属和硫黄直接反应法、氢化铈和三硫化二铈合成法以及电解法比较，硅热还原法所需的设备更为简单实用。     

专利介绍

CN1514042A一种高纯铝钪合金的生产方法本发明是一种高纯铝钪合金的生产方法。这是一种利用现有三层液铝精炼电解槽,在电解质中加入氯化钪或氟化钪,电解生产高纯铝钪合金的方法。其特征在于将氯化钪或氟化钪加入三层液铝电解的电解质中直接电解生产高纯铝钪合金,电解质采用氟氯化物或纯氟化物,其操作控制参数为:电解温度65~850℃,电解槽工作电压4.0~7.0V,电解质厚度4.0~15.0cm。本发明采用在三层液铝精炼电解槽中直接添加氯化钪或氟化钪,使钪与铝共同电解析出的方法,直接生产高纯铝钪合金,可大幅提高铝钪合金质量,同时可提高金属回收率,降…     

碳热还原制取低铝硼铁的方法简介

介绍了碳热还原制取低铝硼铁的一些生产方法,并指出了碳热还原法尚需研究解决的一些主要问题     

Preparation of Scandium-Bearing Master Alloys by Aluminum-Magnesium Thermoreduction

The new preparation method of scandium-bearing master alloys, in which scandium oxide was fluorinated by reaction with NH4HF2 and then reduced by aluminum-magnesium in fused salt containing alkali and alkaline fluoride under atmosphere, was studied. The effect of sorts of metallic reductive and technique conditions such as reducing temperature and time on the recovery of Sc was discussed. When the liquid aluminum-magnesium was used as the reductive agent, the all-recovery exceeds 80% and the concentration of Sc in master alloy prepared exceeds 1.9%. The best reducing reaction temperature and time are 1100 K and 40 rain respectively. The newly produced Sc from reduction combines with A1 to produce the stable compound Al3Sc, so the reduction progress is sustained and the recovery of Sc is increased.     

微量钪对Al-Mg-Mn合金组织与性能的影响

采用铸锭冶金法制备了Al-Mg-Mn和Al-Mg-Mn-Sc两种合金，利用TEM和金相显微镜等手段研究了微量Sc对Al-Mg-Mn合金组织与性能的影响。结果表明：加入微量Sc可以提高Al-Mg-Mn合金的拉伸力学性能。在电镜下可以观察到，在Al-Mg-Mn合金中加入微量Sc可以形成大量弥散的Al3Sc粒子，这些粒子对位错具有钉扎作用。     

Influence of crystallization conditions on the structure and modifying ability of Al–Sc alloys

The influence of the modes of thermal-and-temporal treatment and cooling rate of metallic alloys on crystallization regularities of Al–Sc alloys and their structure, properties, and modifying ability are established. Castings of Al–Sc alloy, which were prepared by the electrolysis of salt melts KF–NaF–AlF₃–Sc₂O₃ at 820–850°C, are used as the initial charge for casting. It is established that, by varying the magnitude of melt overheating and casting temperature, it is possible to vary the crystal shape, amount, and size in wide limits. The modifying action of cast and rapidly quenched master alloys, as well as the master alloy produced by electrolysis, is tested for Al–4.5% Cu alloy. The largest effect of milling the structure of the Al–4.5% Cu–0.4% Sc alloy is attained when using the rapidly quenched master alloy.     

电解铝钪合金的热力学

简要介绍了铝—钪合金的优异性能 ,发展现状 ;提出了利用未经高度提纯的氧化钪 ,直接在电解槽中电解铝—钪合金的工艺方案 ;对该方案的反应热力学数据进行了计算 ,并利用Miedema模型对钪在铝中的活度系数进行了计算。结果表明 :在电解条件下 ( 12 2 3K) ,钪与铝共同析出时 ,在铝液中的平衡活度最大可以达到 2 33 %。加之钪与铝生成稳定的高熔点化合物 ,使钪在铝中的活度系数远小于 1,从而使在电解槽中直接生产含钪在 2 %左右的铝钪合金成为可能。     

Structural Features of Al–Hf–Sc Master Alloys

Microstructural features of new master alloys of the Al–Hf–Sc system with metastable aluminides with a cubic lattice identical to the lattice of a matrix of aluminum alloys are investigated using optical microscopy, scanning electron microscopy, and electron probe microanalysis. Binary and ternary alloys are smelted in a coal resistance furnace in graphite crucibles in argon. Alloys Al–0.96 at % Hf (5.98 wt % Hf) and Al–0.59 at % Hf (3.77 wt % Hf) are prepared with overheating above the liquidus temperature of about 200 and 400 K, respectively. Alloys are poured into a bronze mold, the crystallization rate in which is ~10³ K/s. Metastable Al₃Hf aluminides with a cubic lattice are formed only in the alloy overheated above the liquidus temperature by 400 K. Overheating of ternary alloys, in which metastable aluminides Al _n (Hf_1–xSc _x ) formed, is 240, 270, and 370 K. Depending on the Hf-to-Sc ratio in the alloy, the fraction of hafnium in aluminides Al _n (Hf_1–xSc _x ) varies from 0.46 to 0.71. Master alloys (at %) Al–0.26Hf–0.29Sc and Al–0.11Hf–0.25Sc (wt %: Al–1.70Hf–0.47Sc and Al–0.75Hf–0.42Sc) have a fine grain structure and metastable aluminides of compositions Al _n (Hf_0.58Sc_0.42) and Al _n (Hf_0.46Sc_0.54), respectively. Sizes of aluminides do not exceed 12 and 7 μm. Their lattice mismatch with a matrix of aluminum alloys is smaller than that for Al₃Sc. This makes it possible to assume that experimental Al–Hf–Sc master alloys manifest a high modifying effect with their further use. In addition, the substitution of high-cost scandium with hafnium in master alloys can considerably reduce the consumption of the latter.     

Mechanical properties and microstructures of Al-Mg-Sc alloys

The mechanical properties of Al-(Mg)-0.5Sc alloys have been investigated. Room-temperature tensile and toughness properties were found to reflect a superposition of the properties of Al-Mg and Al-0.5Sc alloys and are quite competitive with high-performance Al alloys. A combination of substructure refinement by Mg and stabilization by Al₃Sc precipitates produces exceptional superplasticity as exemplified by superplastic forming (SPF) elongations in excess of 1000 pct at a strain rate of 0.01 s^-1. Overall, these alloys demonstrate an extremely attractive combination of strength, toughness, density, and SPF fabricability.     

Effect of dispersed Al<Subscript>3</Subscript>Sc particles on dynamic recrystallization in P/M 7000 series alloys

Al₃Sc particles are well known to be a recrystallization inhibitor in Al alloys. In this study, 0.4, 0.8 and 1.5 mass% Sc were added to 7000 series Al alloys in supersaturation by using powder metallurgy. By subjecting rapidly solidified powders of these alloys to a heat treatment at 773 K, Al₃Sc particles were precipitated in the matrix. Subsequently, hot extrusion was carried out at 773 K. During extrusion, continuous dynamic recrystallization (DRX) occurred and fine DRX grains with a diameter of 1 mm were formed. The number of DRX grains was the largest in the 1.5Sc alloy. Even though the amount of Sc added in this case was two times larger, the number of DRX grains in 0.4Sc was almost the same as that in 0.8Sc. Since continuous DRX occurs only under conditions where the grain boundary mobility is low, the number of DRX grains is strongly related to the pinning force on the initial grain boundary exerted by Al₃Sc particles. The pinning force varied with the diameter and volume fraction of Al₃Sc particles. When the pinning force was calculated from the diameter of Al₃Sc particles, which was measured by TEM, it was proven that the number of DRX grains was proportional to the calculated pinning force. Except in the case of 0.4Sc, the Al₃Sc particle diameter was twice that obtained at the maximum pinning force (d _max ). It is possible to promote continuous DRX by decreasing the Al₃Sc particle diameter in 0.8 and 1.5Sc alloys. Lowering the heating rate before heat treatment for degassing reduced the critical nucleus size for precipitation of Al₃Sc particles as well the diameter of Al₃Sc particles. Thus, the pinning force increased in 0.8Sc and 1.5Sc alloys, and the number of DRX grains also increased, as expected.     

Effect of scandium on the phase composition and hardening of casting aluminum alloys of the Al–Ca–Si system

The phase composition of the Al–Ca–Si–Sc system is investigated in aluminum corner uisng computational (Thermo-Calc) and experimental (optical microscopy, scanning electron microscopy, and electron probe microanalysis) methods. The influence of annealing on the structure and hardness of alloys containing 0.3 wt % Sc is investigated in the region up to 550°C. It is shown that the maximum in the hardening curve caused by the isolation of nanoparticles of the Al₃Sc (L1₂) is attained after annealing at temperatures of 300–350°C in alloys belonging to the phase region (Al) + Al₄Ca + Al₂Si₂Ca ((Al) is the aluminum-based solid solution). Scandium completely enters the (Al) composition in alloys of this region, while the silicon concentration is minimal in it. On the other hand, hardening is almost absent in alloys from the (Al) + (Si) + Al₂Si₂Ca phase region. The possibility in principle to form the casting alloys based on the (Al) + Al₄Ca + Al₂Si₂Ca eutectic hardened without quenching is substantiated.     

Synergetic effect in modifying with master alloys having an aluminide cubic structure

Experimental data on the preparation of test master alloys Al–Sc–(Zr, Ti, Y), Al–Zr–(Ti, Y), and Al–Ti–Y, which contain two transition metals and are characterized by the formation of aluminides with the L1₂ cubic lattice (which is identical to the crystal lattice of an aluminum-alloy matrix), are presented. The growth forms of aluminides in alloys of various compositions are demonstrated. Using Al–4% Cu model alloys (experiments were carried out with 15 and 200 g samples cooled at different cooling rates), the modifying ability of the test ternary master alloys and industrial binary master alloys (used for comparison) has been estimated. Synergetic effects of two transition metals, which consist in grain refining in Al–4% Cu alloys, and a substantial difference in the modifying effects of the binary and ternary master alloys have been shown.