铝合金旋转喷吹净化工艺的研究

从表征流态的物理量出发,通过计算建立了铝合金旋转喷吹除气系统的物理模型,以CO2-NaOH体系来模拟实际的铝液净化,用CO2通入溶液后引起的pH的变化来模拟铝液中含氢量的变化.研究了影响铝合金旋转喷吹净化的因素,结果表明转子转速对净化效果影响最大,气流量次之.通过模拟实验获得最佳工艺参数及工艺参数的选取原则,并通过传统的C2Cl6的净化工艺和旋转喷吹净化工艺的比较中证实了旋转喷吹净化工艺优异的除氢效果.

氧化钙坩埚在高纯净化合金研究中的应用

研究了在真空感应炉中使用氧化钙坩埚熔炼金属和合金的净化工艺．采用炉内打结感应烧结的方法，在10kg真空感应炉中制成了具有良好精炼和保温性能的氧化钙坩埚通过添加A1，La和Ca对纯铁和GH169合金进行了净化实验结果显示，采用氧化钙坩埚，在真空度为1．5—2．5Pa，1400℃下精炼，添加A1和La作为净化剂，精炼45min后氧和氮含量均降至20×10－4％（质量分数）以下，硫含量降至3×10-4％（质量分数）以下、还对氧化钙坩埚参与去除合金中硫。

铝合金熔体净化技术的现状及其发展趋势

简单介绍了铝合金熔体中的气体和非金属夹杂物以及两者之间的相互作用,扼要分析了各种铝合金熔体净化处理方法的现状并对铝合金熔体净化技术发展趋势作了展望。

铝合金熔体旋转喷吹除气净化设备的研制

针对铝合金熔体除气净化方面存在的问题,对铝合金熔体旋转喷吹除气净化设备进行研究。对设备主体的各个组成部分进行了分析与设计,尤其是对旋转喷吹组件的设计,提出了在转杆内部安装一条进气管道,降低管道内部温度,有效防止喷射熔剂因高温变软堵塞喷头。对设备气路系统,重点从气路系统的进气环节和调节环节进行设计,提出利用数字组合阀原理进行间断性改变进气流量的思路,可在一定旋转速度下,增加进气流量而不引起铝合金熔体翻腾。从硬件和软件方面对设备先进控制技术方案进行了研究。硬件方面利用西门子PLC对控制系统各组成环节控制原理与方法进行研究。软件方面采用西门子S7-200系列编程软件STEP7编写了设备控制软件。同时,充分考虑设备安全可靠性,设计了手动控制和自动控制两种模式,在自动控制模式下设计紧急停止,防止紧急情况下不良后果恶化。

冶炼洁净钢应用的复合净化剂合金

从冶炼洁净钢的要求出发，根据洁净钢的脱氧制度要求，提出了用于洁净钢冶炼的复合净化剂合金的设计原则及制取方法。同时讨论了设计出的复合净化剂合金在各洁净钢钢种中的冶炼效果。

大厚度Ni_(75)B_(17)Si_8非晶合金的制备

研究了净化Ni_(75)B_(17)Si_(8)合金液的方法以及净化对非晶形成能力的影响,通过净化工艺消除合金液内的异质质点可提高合金液的非晶形成能力;釆用净化和急冷相结合的工艺制备出了20×10×0.5(mm^3)的Ni-(75)B_(17)Si_(8)非晶合金试样。

TiO_2与MnCl_2对Mg合金旧料组织性能的影响

测试了含有不同量的TiO_2或MnCl_2的熔剂对Mg合金废旧料的力学性能、组织、断口形貌以及腐蚀行为的影响,结果表明,TiO_2和MnCl_2均可以降低Mg合金废旧料中的Fe含量,TiO_2的除Fe效果可达0.0053％以下,优于MnCl_2的效果,通过降低Fe量可以提高试样的σ_b和δ,MnCl_2的效果优于TiO_2,采用含30％TiO_2或MnCl_2的熔剂对Mg合金废旧料进行净化处理后,其σ_b和δ可分别大于185.3 Mpa和3.71％,即达到了AZ91 Mg合金新料的性能指标,研究还表明,TiO_2或MnCl_2加入量一定时,均可以提高Mg合金的耐蚀性,但当熔剂中MnCl_2的含量高于30％时,Mg合金的耐蚀性反而下降,TiO_2有助于使γ相成粒状或小岛状析出,并具有很好的细化晶粒的效果。

镁合金薄壁复杂构件砂型铸造技术及应用

由于镁合金壳体铸件材料特点及结构的限制,采用传统的重力铸造合格率难有大幅的提高。因此,亟待寻找一种新的工艺方法代替重力铸造工艺生产壳体铸件,提高壳体铸件的生产效率、降低壳体铸件的废品率,并满足现代战机对构件高强度、高抗腐蚀性的需要,以保证生产的顺利进行。

Effect of inclusion on service properties of GW103K magnesium alloy

The effects of inclusions on microstructure, mechanical property, corrosion behavior of Mg-10Gd-3Y （GW103K） alloys by unrefining, MgO ceramic filtering and JDMJ flux refining were investigated, respectively. The results indicate that with decreasing significantly the number and size grade of inclusions for the alloy refined with JDMJ flux, tensile strength and elongation increase; however, the yield strength is less than that of the alloy refined with MgO ceramic filter and unrefined alloy. With the decrease of the inclusions contents, the corrosion rate of the alloys quickly vary from 2.419 mg/（cm 2 ·d） to 1.265 mg/（cm 2 ·d）. After inclusion content is reduced to 0.385%, the corrosion rate has almost no changes. Finally, the relationship between the volume fraction of inclusions and service properties of GW103K alloy under different conditions are established quantitatively.

Melting purification process and refining effect of 5083 Al-Mg alloy

To improve the poor stability of casting process of Al alloy with high Mg content, which leads to poor final product quality, the melting purification process and the influences of the refiner on the microstructure and defect of 5083 alloy were studied. The results show that the optimized process for the rotary impeller degassing of 5083 alloy is as follows： a rotary speed of 250-400 r/min; a gas flow of 1.2-2.0 L/s, a refining time of 10-15 min. This optimized process can reduce the gas content in the solid alloy to 2× 10^-3 mL/g or lower. Due to the addition of grain refiner, the cast microstructure of 5083 alloy is refined. The Al-5Ti-IB wire shows the best refining effect among all the refiners. The refining effect is improved with the increase of grain refiner addition amount. And the refinement effects become stable when Ti content reaches 0.1% or higher. The surface crinkling defect of the billet can be easily found in the alloy refined with Al-5Ti-IB wire compared with the alloys refined with other refiners.

Effect of purification treatment on corrosion resistance of Mg-Gd-Y-Zr alloy

Mg-Gd-Y-Zr alloys were purified by filtering purification with and without vacuum. The type, morphology, size distribution and volume fraction of inclusion were analyzed with OM and SEM. The effect of inclusion in Mg-Gd-Y-Zr alloys on anticorrosion ability was investigated with salt spray test and electrochemical test. The results show that the inclusions in the alloy can be removed effectively by filtering purification. The average size of inclusions in the alloys is decreased from 12.7 μm to 2.0 μm and the volume fraction of inclusions is reduced from 0.30% to 0.04%. With the decrease of the size of inclusions in the alloys, the corrosion rate of the alloys decreases dramatically from 38.8 g/（m 2 ·d） to 2.4 g/（m 2 ·d） in the salt spray test. The corrosion potential increases while the corrosion current decreases and the polarization resistance increases in the electrochemical tests, which indicates that the anticorrosion ability is improved.

Effect of Nickel Contamination on Formation of Denuded Zone in Czochralski Silicon

The effect of nickel contamination under rapid thermal processing （RTP） on the magic denuded zone （MDZ） in Czochralski silicon is investigated. It is found that the bulk defects can effectively getter nickel atoms once the MDZ forms. However,if the silicon sample is initially contaminated with nickel, the MDZ cannot form during the subsequent RTP,and a high density of precipitates occurs near the surface. In conventional IG processes,the DZ can form regardless of the nickel contamination sequence. Based on the facts,we propose that the formation of nickel silicide （Ni3Si） at the surface keeps the concentration of vacancies in the near-surface zone still higher than the critical concentration for oxygen precipitation under the subsequent RTP, which prevents MDZ formation.

太原市跃进镁业有限公司

太原市跃进镁业有限公司成立于2004年3月，由太原市同翔金属镁有限公司和上海交通大学“轻合金精密成型国家研究中心”合作，共同创办“镁合金净化及连铸技术产业化示范工程”而建立的镁合金深加工企业，

Effect of complex melt-refining treatment on microstructure and mechanical properties of sand-cast Mg–10Gd–3Y–0.5Zr alloy

The effect of complex melt-refining treatment （melt flux incorporating with rotating gas bubble stirring） on microstructure and mechanical behavior of the sand-cast Mg-10Gd-3Y-0.5Zr alloy was investigated. In addition, the melt purifying mechanism of the complex melt-refining treatment for the sand-cast alloy was discussed systematically. The results show that the new melt-refining method can significantly improve melt quality and mechanical behavior of the tested alloy, i.e., compared to the reference unpttdfied alloy, the volume fraction of inclusions decreased from 0.47% to 0.28%, the ultimate tensile strength and elongation for T6-treated alloy increased from 245 MPa and 0.7% to 312 MPa and 4.5%, respectively. Especially, combining 1% flux with rotating gas bubble stirring can get even better purifying effectiveness than conventional sole 2% flux purification; the use of melt flux decreased by 50% and significantly reduced environmental pollution.

Effect of purification treatment on properties of Mg-Gd-Y-Zr alloy

Mg-Gd-Y-Zr alloy was purified by the method of filtering purification. The type, morphology, size distribution and volume fraction of inclusions in the alloy were analyzed using optical microscope and scanning electron microscope, and the effects of the inclusions on the mechanical and corrosion properties of the alloy were investigated. The results indicate that the filtering purification method is effective to remove inclusions in the alloy. By the filtering purification method, the average size of inclusions in the alloy reduces from 12.7 μm to 4.3 μm and the average volume fraction of inclusions in the alloy reduces from 0.26% to 0.06%. The ultimate tensile strength, yield strength and elongation of the alloy are improved from 200 MPa, 156 MPa and 3.4% to 232 MPa, 167 MPa and 7.0%, respectively. The corrosion rate of the alloy decreases dramatically from 38.8g/（mLd） to 2.5 g/（mZ.d） in the salt spray test.

Non-flux purification behavior of AZ91 magnesium alloy

The effects of non-flux purification techniques on the mechanical properties and microstructure of AZ91 magnesium alloy were investigated by ICP,OM,XRD and SEM.The results show that Ar spraying with high flow rate could remove non-metallic inclusions and improve the mechanical properties of AZ91.The alloy obtains the best properties after argon spraying for 30 min at the melt temperature of 740 °C.The ceramic foam filter(CFF) could effectively improve the ultimate tensile strength and elongation of AZ91 alloy,especially the elongation,which increase with increasing pores per inch(ppi) and the thickness of CFF.Non-flux purification does not change the microstructure of AZ91 alloy.However,filtration has a certain effect on the fracture pattern of AZ91 alloy.To improve the mechanical properties effectively,both filtration and gas spraying should be utilized together.

Numerical simulation of standing waves for ultrasonic purification of magnesium alloy melt

It was attempted to enhance and accelerate the separation of oxidation inclusions from magnesium alloy melt by virtue of ultrasonic agglomeration technology.In order to investigate the feasibility and effectiveness of standing waves for ultrasonic purification of magnesium alloy melt,numerical simulation and relevant experiment were carried out.The numerical simulation was broken into two main aspects.On one hand,the ultrasonic field propagations within the cells with various shapes were characterized by numerical solutions of the wave equation and with a careful choice of geometry a nearly idealized standing wave field was finally obtained.On the other hand,within such a standing wave field the agglomeration behavior of oxidation inclusions in magnesium alloy melt was analyzed and discussed.The agglomeration time and agglomeration position of oxidation inclusions were predicted with numerical simulation method.The results show that the oxidation inclusions whose apparent densities are close to the density of the melt can agglomerate at wave nodes in a short time which to a great extent enhances and accelerates the separation of oxidation inclusions from magnesium alloy melt.

Comparative study on microstructure and electrochemical corrosion resistance of Al7075 alloy prepared by laser additive manufacturing and forging technology

Al7075 alloy is a typical aviation aluminum with good mechanical properties and anodic oxidation effect.Laser engineered net shaping technology has unique advantages in the integrated forming of high-performance large aircraft structural parts.The manufacturing of 7075 aluminum alloy structural parts by laser engineered net shaping technology has become an important development direction in the future aerospace field.Electrochemical corrosion resistance of aluminum alloys is of vital importance to improve reliability and life-span of lightweight components.A comparative study on microstructure and anti-corrosion performance of Al7075 alloy prepared by laser additive manufacturing and forging technology was conducted.There are hole defects in LENS-fabricated Al7075 alloy with uniformly distributedηphase.No defects are observed in Al7075 forgings.The large S phase particles and small ellipsoidalηphase particles are found in Al matrix.The corrosion mechanisms were revealed according to the analysis of polarization curves and corrosion morphology.It was found that compared with that prepared by forgings,the additive manufactured samples have lower corrosion tendency and higher corrosion rate.Corrosion occurred preferentially at the hole defects.The incomplete passivation film at the defects leads to the formation of a local cell composed of the internal Al,corrosion solution and the surrounding passive film,which further aggravates the corrosion.

Influence of GdCl_3 addition on purifying effectiveness and properties of Mg-10Gd-3Y-0.5Zr alloy

In order to improve the purifying efficiency of RJ6 flux,5%(mass fraction) GdCl3 was introduced into the flux for refining Mg-10Gd-3Y-0.5Zr(GW103K) alloy.The results show that the RJ6 flux containing 5%GdCl3 exhibits better adsorption ability to nonmetallic inclusions than the one without GdCl3.Moreover,the mechanical,corrosion properties and fluidity of the alloy refined with RJ6 flux and RJ6 flux containing 5%GdCl3 were investigated,respectively.It is found that these properties are improved to a certain degree due to the removal of nonmetallic inclusions in the alloy.Thermodynamic analysis and surface tension experiments indicate that the main reason can be ascribed to the decrease of the surface tension of the flux with 5%GdCl3,which promotes the combination of flux and nonmetallic inclusions.

Dendritic growth and solute trapping in rapidly solidified Cu-based alloys

Rapid solidification of binary Cu-22%Sn peritectic alloys and Cu-5%Sn-5%Ni-5%Ag quaternary alloys was accomplished by glass fluxing, drop tube and melt spinning methods. The undercooled, by glass fluxing method, Cu-22%Sn peritectic alloy was composed of a（Cu） and δ（Cu41Snll） phases. If rapidly solidified in a drop tube, the alloy phase constitution changed from α（Cu） and δ（Cu41Sn11） phases into a single supersaturated （Cu） phase with the reducing of droplet diameter, and the maximum solubility of Sn in （Cu） phase extended to 22%. The Cu-5%Sn-5%Ni-5%Ag quaternary alloy was composed of （Cu） and （Ag） phases under the containerless processing condition in a drop tube, and the solute microsegregation of （Cu） phase was obvious. When the Cu-5%Sn-5%Ni-5%Ag quaternary alloy was solidified by melt spinning method, microsegregation was suppressed and solute trapping occurred. The experimental results show that the microstructures of primary （Cu） phase in the two alloys transfer from coarse dendrites into equiaxed grains with the increase of cooling rate and undercooling, which is accompanied by the grain refinement effect.