稀土元素对快凝AlFeVSi合金性能和组织的影响

采用力学拉伸试验、透射电镜、扫描电镜等测试手段研究了稀土元素Ｅｒ,Ｙ,Ｃｅ对ＦＶＳ０８１２合金挤压棒材的力学性能和显微组织的影响,并通过考察稀土元素与合金组成元素之间的变互作用强度,定性地分析了稀土元素在快凝ＡｌＦｅＶＳｉ合金中的作用机理。结果表明,Ｅｒ促使粗大块状δ相的形成,加Ｙ则有较粗大的类球形第２相Ａｌ２０（Ｖ,Ｆｅ）２Ｙ的析出,而Ｃｅ没有生成其它相,但是明显细化了Ａｌ１２（Ｆｅ,Ｖ）３Ｓｉ     

Cu对快凝Ni-Al基合金催化剂结构及性能的影响

利用单辊旋铸法制备了不同Cu含量的快速凝固Ni-Al-Cu -Ce合金 ,经碱洗抽Al进行活化 ,制成骨架镍催化剂 .研究了Cu对催化剂先驱体合金的相组成、活化后催化剂的结构及催化性能的影响 .结果表明 ,在Ni-Al-Ce合金中加入 2 % (质量分数 )的Cu有益于催化剂的结构及催化性能的改善 ,而较高的Cu含量则会产生不利的影响 .     

快凝Al-Cr合金的显微结构与形核动力学

用连续冷却的方法对Al (1～ 5 )Cr(质量分数 )快凝合金的形核动力学及显微结构进行了计算与研究 ,得出了在不同成分、不同冷却速度下的形核孕育期与冷却速度之间的关系 ,从而得出了凝固过程中的相选择规律 ,即某相的优先析出是由于其形核动力学条件较其他相更具优势所致 .具体到Al Cr合金 ,则随着溶质含量的提高 ,抑制金属间化合物相首先形核所需的临界冷速增大 ,也即完全过饱和单相α Al的组织只能在很大的冷速或极薄的条带中形成 ,且计算结果与实验检测吻合较好 .     

快凝Al-Ti-RE合金化合物相结构及形成的研究

利用TEM、XRD等分析手段研究快速凝固从Al-Ti-La合金中的化合物相的结构,以及高温退火后的结构,分析化合物相的高温稳定性,并提出化合物相的孪晶形核理论．快速凝固Al-Ti-La合金形成细小、圆整、弥散的金属间化合物相,经分析为Al20Ti2(RE),金刚石立方结构,该化合物相形成孪晶,其孪晶面{111},孪晶方向[112],认为化合物相是以孪晶为晶核从熔体中优先其他化合物相形成并生长．     

快速凝固技术的发展现状与展望

快速凝固技术得到的合金具有超细的晶粒度,无偏析或少偏析的微晶组织,形成新的亚稳相和高的点缺陷密度等与常规合金不同的组织和结构特征,对材料科学及其它学科的理论研究以及满足实际生产中的需要起到了重大的作用。本文详细总结了最基本和目前最新型快速凝固技术的原理、方法以及特点,介绍了快速凝固技术在买际中的应用状况,阐明了快速凝固技术的发展趋势。     

Fe-Si系软磁粉末制备的研究进展及气雾化制粉技术展望

介绍了当今现有的几种Fe-Si系软磁粉末材料制备技术,如机械球磨、水雾化和气雾化等,其中由于气雾化制粉具有环境污染小、粉末球形度高、氧含量低以及冷却速率大等优点,已发展为生产高性能Fe-Si系软磁粉末的主要方法.但是气雾化制粉工艺本身是一个多相流相互耦合作用的复杂过程,因此到目前为止,人们对气雾化机理至今仍未能透彻认识,紧耦合气雾化技术被认为是艺术而不是科学.同时,鉴于气雾化制粉技术应用的广泛性和重要性,简要回顾了气雾化制粉技术的发展历程,并对其发展前景进行了探讨和展望.     

Preparation and microstructure of AI-Ni-Y powder by rapid solidification

1　INTRODUCTIONAluminium basedamorphoushasattractedmoreandmoreattentionforitsgoodmechanicalproper ties[13] .Al basedamorphouswereoftenpreparedbymeltspinningonasinglerollerordoublerollers[4 8] .SincetheglassformingabilityofAlalloyisrelativelylow[9] ,theAl basedamorphouscanonlybepreparedunderhighsolidificationvelocity ,whichresultsinnubAl basedamorphousalloyorfilm(preparedbyionbeamsputtering[10 ] )withorderofμm .Itisverydif ficultforustoproducebulkyAl basedamorphousal loy ,whichalsolimits…     

液态金属的深过冷及其凝固组织

深过冷熔体能够在低速冷却的情况下实现快速凝固 ,因而深过冷技术引起了人们的关注 ,并在这方面取得了很多成果 .本文分析了深过冷的热力学及动力学基础 ,综述了近年来深过冷技术的发展以及人们在其凝固特征方面的研究发现 .随着深过冷工艺的提高 ,可以获得的过冷度已大大超过了以前人们普遍认为均质形核所能达到的最大过冷度 0 .2Tm.深过冷的凝固组织使晶粒细化、杂质分布改善 ,普遍具有强韧化效果 .此外 ,利用深过冷技术还能制备常规凝固条件下不能得到的一些具有优异性能的新材料     

Study on undercooling of metal droplet in rapid solidification

In 1950, Turnbull et al.[1] dispersed 18 kinds of metals including Cu, Ni, etc. into droplets with diameters of 10-100 μm and obtained a large undercooling of 0.18 TL. Volkmann et al.[2] have successfully obtained the undercooling of 0.3 TL in the Co-Pd alloy by means of the molten glass purified technique. As yet, the maximum undercool-ing in liquid metals is acquired by Perepezko et al.[3], who makes the Ga with a diameter of 20 μm reach an undercooling of about 0.58 TL by use of the …     

Flow field simulation of the thin metal ribbon formed by twin-belt rapid solidification

The flow field formed when an aluminum ribbon is produced by twin-belt rapid solidification is simulated with the solu-tion algorithm (SOLA)-volume of fluid (VOF) method, and the influence of casting speed and cooling-belt velocity on the flow field is analyzed for a given ejection nozzle size. It has been found that the flow field can be filled well when the width of the ejection nozzle outlet is the same as that of the up slit of the cooling belt. When the ejection nozzle outlet is wider than the up slit of the cool-ing belt, the aluminum fluid can fill well if only the casting speed matches the cooling-belt velocity properly, otherwise under filling occurs in some areas in the cooling zone.     

液态锌凝固过程中的分子动力学模拟研究

采用Morse势函数,用分子动力学方法研究了冷却速度对液态金属锌凝固过程微观结构的影响.利用径向分布函数、能量分析、Voronoi多面体结构分析等方法分析了凝固过程中的微观结构演变特征.结果表明,冷却速率大于2.5×1012 K/s时,得到非晶态结构;冷却速率小于7.0×10 11K/s时,将发生结晶.同时发现,在结晶...     

Multiple steady states in rapid solidification and the glass transition

Ｔｈｅｇｌａｓｓｔｒａｎｓｉｔｉｏｎｈａｓｂｅｅｎｏｎｅｏｆｔｈｅｃｅｎｔｒａｌｉｓｓｕｅｓｉｎｃｏｎｄｅｎｓｅｄｐｈｙｓｉｃｓｆｏｒｍａｎｙｙｅａｒｓ[1].Ｉｎｏｒｄｅｒｔｏｅｘｐｌａｉｎｔｈｅｐｈｙｓｉｃａｌｎａｔｕｒｅｏｆｔｈｅｇｌａｓｓｔｒａｎｓｉｔｉｏｎ,ａｎｕｍｂｅｒｏｆｔｈｅｏｒｅｔｉｃａｌｍｏｄｅｌｓｆｏｒｔｈｅｇｌａｓｓｔｒａｎｓｉｔｉｏｎ[2—8]ｈａｖｅｂｅｅｎｐｒｏｐｏｓｅｄ.Ｈｏｗｅｖｅｒ,ｉｔｓｅｅｍｓｔｈａｔａｇｅｎｅｒａｌｓａｔｉｓｆｙｉｎｇｔｈｅｏｒｅｔｉｃａｌｄｅｓｃ…     

快速凝固条件下Cu-Cr合金的液相分解

采用快速凝固方法研究了Cu100-xCrx(x=2，25和35％)合金凝固行为．利用带有能谱(EDS)的扫描电子显微镜(SEM)分析了Cu—Cr合金的显微组织形貌和成分．实验结果证实，Cu—Cr合金在快速凝固过程中发生了液相分解，在较大的富Cr液相分解球中可观察到来自于二次相分解的、更细小的富Cu粒子．与Cu—Co和Cu-Fe液相分解组织不同，快速凝固Cu-Cr合金的大尺寸液相分解球不是由相互表面界限明确的、尺寸更小的液相分解球所组成，而是一个整体结构．     

Size distributions and magic number characteristics of cluster configurations formed during solidification processes of liquid metal Al

Recently, the studies on the stability and magic number characteristics of cluster con- figurations, especially of larger cluster configurations, have become a very active area in physics, chemistry and materials science[1―8]. However, at present, the experimental stud- ies are mainly carried out on fine powder obtained by means of physical or chemicalmethods (such as ionic spray, laser evaporation, air-actuated technology, gas discharging, and organic metal chemical reaction) [1-5], and the t…     

Fabrication of directional solidification components of nickel-base superalloys by laser metal forming

Straight plates, hollow columns, ear-like blade tips, twist plates with directional solidification microstructure made of Rene 95 superalloys were successfully fabricated on Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for production of the parts with corresponding shapes were obtained. The fabrication precision was high and the components were compact. The solidification microstructure of the parts was analyzed by optical microscopy. The results show that the solidification microstructure is composed of columnar dendrites, by epitaxial growth onto the directional solidification substrates. The crystallography orientation of the parts was parallel to that of the substrates. The primary arm spacing was about 10μm, which is in the range of superfine dendrites, and the secondary arm was small or even degenerated. It is concluded that the laser metal forming technique provides a method to manufacture directional solidification components.     

基于快速制模的铝粉室温分层粘结试验研究

以简化塑料模具的快速制造工艺为出发点，以铝粉为基料，对比分析室温固化胶粘剂如环氧树脂，改性丙烯酸酯，硅橡胶在室温下进行分层粘结和固化的试验结果，指出改性丙烯酸酯对于铝粉室温分层粘结有着较好的前景。