热等静压FGH95粉末涡轮盘

采用氩气雾化和等离子旋转电极雾化两种制粉工艺制备的ＦＧＨ９５粉末和双韧化（颗粒界面韧化＋热处理强韧化）热等静压近尺寸成形盘件制备工艺,制备了ＦＧＨ９５粉末涡轮盘。性能达到国外同类合金的Ａ级水平并装机通过了发动机的盘件结构试验与试车。     

元素粉末法制备TiAl金属间化合物的研究进展

元素粉末冶金因具有成本低、制备的合金组织均匀细小等优点而受到广泛关注。简要介绍了元素粉末法制备TiAl合金的研究进展,主要从反应机理、致密化行为和力学性能等方面进行综述。研究表明,Ti与Al元素的反应由扩散控制,借助TiAl3和TiAl2等中间相最终得到Ti3Al和TiAl相共存的反应产物。在高Nb–TiAl合金的Ti–Al–Nb三元系中,Nb元素主要通过形成中间产物——Nb–Al化合物最终均匀分布在基体相中。从原料和工艺两个角度总结了元素粉末法制备TiAl合金过程中影响致密化的因素,介绍了提高元素粉末法制备TiAl合金的热加工和力学性能的方法,总结了近年来元素粉末法制备TiAl合金的力学性能研究成果。目前来看,元素粉末法制备的TiAl合金力学性能已达到变形合金的水平。     

粉末冶金TiAl金属间化合物的研究进展

从粉末制备、成形、烧结、热处理等方面综述了粉末冶金方法制备TiAl金属间化合物的最新进展.着重评述了粉末冶金TiAl基合金的几种烧结工艺,其中包括热等静压、自蔓延高温合成、粉末注射成形、放电等离子烧结等,同时论述了上述各方法的优势以及局限性,并指出了今后的研究方向.     

增材制造技术制备钛铝合金的研究进展

增材制造技术(也称3D打印技术)在发展新型TiAl合金领域有巨大潜力。电子束熔炼技术制备TiAl合金逐渐引起关注,本文对相关工艺探索的研究进行了综述。通过调节EBM过程中的各工艺参数,例如片层厚度、熔炼温度、扫描速率、线能量和构建路径等参数,可获得致密并且无大量Al损失的均匀样品。经过热等静压处理和热处理,可得到细小均匀的组织。通过控制热处理温度,可获得等轴近Gamma组织、双态组织(片层比率不同)或全片层组织。介绍了高Nb-TiAl合金合金粉末、块体材料制备工艺对组织的影响等。总结了EBM技术的优点和存在问题(包括解决缩孔、Al损失、组织和性能的精确控制等问题),并对其发展前景进行了展望。我国利用EBM技术制备Ti合金的研究工作刚开始,尚未开展制备TiAl合金的研究工作。     

气雾化钛合金粉末快速凝固过程模拟

气雾化制粉技术是目前制备球形钛合金粉末应用最广泛、最成熟的技术之一.基于流体力学模拟方法,粉末破碎机理研究获得了很大进步.而存气雾化制粉过程中,金属熔滴在高速气流的强制冷却作用下快速凝固形成粉末颗粒,很大程度上决定了粉末的微观组织及性能.针对熔滴快速凝固过程,利用Fluent软件模拟雾化气体与合金熔滴之间的热量传输过程...     

粉末高温合金研究进展

粉末高温合金是制造高性能航空发动机涡轮盘等转动部件的关键材料.针对国外粉末高温合金的研究历史和现状,结合粉末高温合金的制备工艺流程,重点介绍了美国和俄罗斯粉末高温合金的发展现状,对比分析了不同粉末制备工艺、粉末固结工艺、盘件成形工艺的特点,总结了粉末高温合金中存在缺陷的原因及控制方法.针对我国粉末高温合金的研究历史和现状,总结了国内粉末高温领域所取得的进展.对国内外粉末高温合金在航空发动机上的应用进行了总结.对超纯净度细粉制备、直接热等静压近终成形、双性能粉末涡轮盘制备工艺等高性能粉末高温合金的关键技术及发展方向进行了展望.针对国内对粉末高温合金的需求现状,指出了国内粉末高温合金研制和生产过程中存在的问题并给出了相应的解决思路.     

非接触式测试技术在气雾化制粉研究中的应用

气雾化制粉是目前大规模制备高品质合金粉末的主流工艺,在粉末冶金、增材制造、热喷涂、钎焊等领域具有广泛的应用价值。雾化过程决定最终粉末的品质,因此开展气雾化过程研究具有重要的意义。传统研究气雾化制粉过程的方法多采用接触式测试技术,通过设计实验间接进行研究,存在周期长、成本高、与实际工况差别较大、无法进行瞬态研究等缺点,对气雾化机理研究和气雾化系统结构设计的指导价值非常有限。近年来,国内外学者借鉴流体力学领域的一些测试技术,开展了气雾化过程非接触式测试实验研究。根据研究对象分类,对适用于流场形貌、速度分布、液滴粒径分布以及温度场研究的非接触式测试技术进行了综述,阐述了这些技术的原理以及应用,并对气雾化过程测试技术的未来发展方向进行了展望。     

TiAl合金粉末热等静压组织及其力学性能均匀性研究

目的 研究圆柱包套经热等静压后内部不同位置粉末TiAl合金的组织与力学性能,为后续复杂结构包套热等静压整体成形工艺优化提供参考.方法 将装填有Ti-47Al-2Cr-2Nb雾化粉末的不锈钢包套在1230℃/170 MPa/3.5 h条件下热等静压,利用扫描电子显微镜观察烧结后包套内不同区域的显微组织,利用显微硬度计测量...     

陶瓷用Ag-Cu-Ti焊料制备工艺的研究

采用2种粉末成形制备方法,研究了Ag-Cu-Ti合金的制粉工艺、粉末成形工艺、烧结工艺、热处理工艺及片材轧制工艺,获得了成分均匀、氧含量低、厚度为0.1 mm的陶瓷用Ag-Cu-Ti焊料,比较了2种成形制备工艺的性能.     

Ti55粉末合金的拉伸性能和薄壁筒体结构的成型

采用包套热等静压工艺制备了洁净Ti55粉末合金。根据Ti55预合金粉末的β转变温度选择了两个热等静压成型温度,分析了Ti55粉末合金对热等静压温度和后续的热处理制度的响应。结果表明:在940℃和970℃热等静压成型的粉末合金,其显微组织和拉伸性能的差别不大。考虑到在构件热等静压成型过程中存在温度/压力场分布不均匀引起的致密化波动效应,本文优选的热等静压温度为940℃。固溶时效热处理使粉末合金600℃的拉伸性能显著提高,其拉伸性能优于铸造合金,接近锻造合金的水平。有限元模拟仿真可辅助包套/模具设计,提高效率,是粉末冶金近净成型构件制备的有效计算仿真工具。应用有限元仿真辅助包套模具设计,采用热等静压工艺成型了Ti55粉末冶金薄壁筒体结构。     

A Novel near Net—Shape Technique for P／M Parts with Large H／D Ratio

In order to overcome the shortcomings of conventional hot pressing,a novel near net-shape technique,called radial hot pressing,for P/M parts with large height-to-diameter (H/D) ratio was introduced.Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied.Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1,and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.     

热等静压温度和粉末粒度对Ti2AlNb合金组织与性能的影响

采用无坩埚感应熔炼超声气体雾化法制备了成分为Ti-22Al-24Nb-0.5Mo(原子分数, %)的预合金粉末,通过预合金粉末热等静压工艺制备了Ti₂AlNb粉末冶金合金。研究结果表明,热等静压温度显著影响Ti₂AlNb粉末冶金合金的显微组织,需严格控制。为了对比研究,选取了平均粒度分别为70 μm和200 μm的两种Ti₂AlNb预合金粉末,制备坯料并测试性能,探讨了粉末粒度的选取原则,分析了粉末粒度对Ti₂AlNb粉末冶金合金显微组织和力学性能的影响。研究结果表明,粉末粒度对合金室温拉伸强度无显著影响,但会对高温拉伸强度和高温持久寿命产生显著影响,由粗粉(平均粒度200 μm)制成的合金高温持久寿命较细粉(平均粒度70 μm)的降低大约40%。     

Microstructure Design and Heat Response of Powder Metallurgy Ti_2AlNb Alloys

Pre-alloyed powder of Ti-22Al-24Nb-0.5Mo(atomic fraction,%) was prepared by gas atomization.Powder metallurgy(PM) Ti_2AlNb alloys were prepared by a hot isostatic pressing(HIPing) route.The influence of experimental variables including HIPing temperatures,solution and aging temperatures on microstructure and properties of PM Ti_2AlNb alloys was studied.The results showed that HIPing temperature affected the porosity distribution and mechanical properties of PM Ti_2AlNb alloys.The microstructure and mechanical properties of the PM Ti_2AlNb alloys changed obviously after various post heat treatments,and a good combination of tensile strength,ductility and rupture lifetime was obtained through an optimized heat treatment in the present work.     

Microstructure of AA2024-SiC nanostructured metal matrix composites

Nanostructured metal matrix composites (NMMCs) in large-dimension billets were fabricated by hot isostatic pressing (HIPing) of cryomilled powders consisting of AA2024 alloy reinforced by 25 wt.% SiC particles. Microstructure of the bulk nanostructured composites and cryomilled powders was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In addition, mechanical properties of the bulk nanocomposites were also addressed.     

Microstructures and Mechanical Properties of Rapidly Solidified Mg-Al-Zn-MM Alloys

Mg-Al-Zn-M M （misch metal） alloy powders were manufactured by inert gas atomization and the characteristics of alloy powders were investigated.In spite of the low fluidity and easy oxidation of the magnesium melt,the spherical powder was made successfully with the improved three piece nozzle systems of gas atomization unit. It was found that most of the solidified powders with particles size of less than 50μm in diameter were single crystal and the solidification structure of rapidly solidified powders showed a typical dendritic morphology because of supercooling prior to nucleation.The spacing of secondary denrite arms was deceasing as the size of powders was decreasing.The rapidly solidified powders were consolidated by vacuum hot extrusion and the effects of misch metal addition to AZ91 on mechanical properties of extruded bars were also examined.During extrusion of the rapidly solidified powders,their dendritic structure was broken into fragments and remained as grains of about 3μm in size.The Mg-Al-Ce intermetallic compounds formed in the interdendritic regions of powders were finely broken,too.The tensile strength and ductility obtained in as-extruded Mg-9 wt pct Al-1 wt pct Zn-3 wt pct MM alloy wereσ-（T.S.） =383 MPa andε=10.6%,respectively.All of these improvements on mechanical properties were resulted from the refined microstructure and second-phase dispersions.     

Consolidation of nanoscale iron powders

The consolidation behavior of two types of nanoscale iron powders-vacuum condensed (nanograins in nanoparticles) and ball-milled (nanograins in microparticles), was studied. The consolidation of two microscale powders, atomized and ground, was also characterized for comparison. Consolidation techniques investigated were cold closed die-compaction, cold isostatic pressing (CIPing), and after CIPing, sintering or hot isostatic pressing (HIPing). The mechanical properties, density, and microstructure of the resulting compacts were found to depend on the original powder type and its consolidation history. Significant differences were found between the microscale and nanoscale powders. An additional reason, besides the dissimilarity in grain size, for the differences observed relates to the fact that the nanograin powders contained significant amounts of oxygen, which ultimately resulted in a distinctly two-phase bulk microstructure. The vacuum condensed powder achieved satisfactory green strength on CIPing, and high hardness (440 Hv) on low temperature sintering. While unnecessary for complete consolidation, HIPing at 500 °C was found to be beneficial and compacts of this powder thus treated were found to have a hardness of 520 Hv and high compressive yield strength (1800 MPa). For ball-milled powders, HIPing was found to be essential for achieving effective consolidation: ball-milled material, which remained friable after CIPing and sintering at 580 °C, achieved exceptionally high hardness (820 Hv) when HIPed at 580 °C and 175 MPa. The ductility was greatly improved when HIPed at temperatures between 700 °C and 850 °C, while preserving its relatively high strength. The behavior of these nanoscale powders can be understood by invoking the usual densification, particle bonding, and grain growth mechanisms. Optimization of these processes may result in unique mechanical properties of ball milled powders.     

483Q发动机用TiAl基合金排气阀门的研制

利用真空感应凝壳熔炼设备熔铸了 Ti Al合金 483Q发动机的排气阀门坯件 ,经热等静压及机械加工后所制得的 Ti Al合金排气阀门重量比原材质的减少了 49.3%。 483Q台架试验测试结果表明 ,Ti Al合金适宜于制造 483Q发动机排气阀门。     

Densification of sintered lead zirconate titanate by hot isostatic pressing

The effects of hot isostatic pressing (HIPing) on sintered lead zirconate titanate are presented. Densities up to 98% were obtained by HIPing for 1 h at 1300°C with argon gas pressures of either 20.7 or 138 MPa. The microstructural changes observed after HIPing, and the rapid initial kinetics for densification and pore shrinkage, indicate that prssure-enhanced grain rearrangement and solution-precipitation processes are primarily responsible for densification. The persistance of large voids after HIPing suggests that it may be impossible to completely eliminate gross processing-related defects in lead zirconate titanate by HIPing.     

Increasing the amorphous yield of {(Fe0.6Co0.4)0.75B0.2Si0.05}96Nb4 powders by hot gas atomization

The synthesis of metallic glasses requires high cooling rates leading to product size limitations of a few millimeters when using conventional casting techniques. One way to overcome these size limitations is powder metallurgy. Melt atomization and the subsequent powder processing can result in larger, amorphous components as long as no crystallization takes place during powder consolidation.An iron-based glass-forming alloy {(Fe_0.6Co_0.4)_0.75B_0.2Si_0.05}₉₆Nb₄ was formed through both ambient room and high temperature inert gas atomization at various melt flow rates (close-coupled atomization). The use of hot gas generally decreases the droplet size and hence leads to an increased cooling rate and amorphous fraction of the atomized powders.Hot gas atomization results in a lower gas consumption, a smaller gas-to-melt mass flow ratio (GMR), smaller particles and a smaller geometric standard deviation.Particles atomized in ambient temperature were fully amorphous up to a particle size fraction of 90?µm. Larger particle size fractions resulted in a higher crystalline fraction. According to the XRD and DSC analyses, hot gas atomization has only a very small influence on the cooling rate and the amorphous fraction. However, the amorphous yield is significantly increased using hot gas atomization.     

Reaction synthesis of titanium aluminides

The formation of titanium aluminides from the elemental powders has been investigated. A traditional powder metallurgy route of compaction (by cold isostatic pressing, hot pressing or hot extrusion) followed by heat treatment was compared with the novel technique of hot extrusion reaction synthesis (HERS). The products from these different production methods were characterised by x-ray diffraction and microscopy (light and scanning electron). The intermetallic compound formed under most processing conditions wasTiAl₃. Only when there was a rapid increase in temperature to high temperatures, as found in induction heating of compacts or in HERS, were the compounds Ti₃Al and TiAl formed.