有利于铸造TiAl合金增压器涡轮叶片可靠性的组织设计

针对增压器涡轮应用背景,详细分析定向层片组织铸造TiAl合金的室温拉伸塑性、断裂韧度以及高温热暴露后的剩余塑性等反映叶片抗损伤能力的性能,并讨论在叶片中形成这种定向层片组织的工艺可行性,以获得一种有利于增压器涡轮可靠性的组织设计。结果表明:定向层片组织铸造TiAl合金具有优异的室温拉伸塑性和断裂韧度,并且在高温热暴露后仍能保持较高的室温拉伸塑性,这些优异性能均依赖于定向层片取向一致性特征。通过控制凝固冷却条件和Ti/Al原子比,在增压器涡轮叶片中可以获得层片界面近似平行叶片表面的定向层片组织,有利于提高叶片的抗损伤能力,从而改善TiAl合金增压器涡轮的使用可靠性。     

铸造用TiAl母合金制备技术研究进展

目前,新型轻质高温结构材料TiAl合金铸造部件已经进入工业化生产阶段,急需工业级铸造用TiAl母合金的制造技术和评估体系作为支撑。结合了钢铁研究总院铸造TiAl合金工程化研究和应用成果,概述了国内外铸造TiAl合金材料和部件的工程化应用现状,在此基础上,提出了铸造TiAl母合金的化学成分、规格等技术要求,并进一步对比分析了2次自耗熔炼、自耗熔炼+凝壳熔炼、自耗熔炼+凝壳熔炼+自耗熔炼等母合金制备工艺的优缺点,最后提出了工业级铸造TiAl母合金的技术发展方向。     

TiAl合金气雾化制粉及热等静压成形研究进展

概述了TiAl合金气雾化制粉及热等静压成形的主要研究成果。在TiAl合金粉末制备方面,重点介绍了气雾化制粉工艺、粉末粒度控制、粉末氧含量控制和粉末组织特征。针对热等静压技术,介绍了TiAl合金粉末热等静压致密化过程及机理,总结了采用热等静压近净成形工艺制备TiAl合金转捩片的研究成果。结合粉末冶金TiAl合金研究进展,提出了未来TiAl合金粉末制备及成形技术的发展方向。     

高铌TiAl高温合金的研究现状与展望

高铌TiAl高温合金是一种具有发展前途的新一代高温结构材料,合金化元素铌的添加能够显著提高γ-TiAl合金的工程应用.文章首先综述了高铌TiAl合金的性能特点和应用前景,并简单介绍了该合金的最新基础研究情况,随后介绍了制备高铌TiAl合金的基本工艺.最后论述了国内外高铌TiAl高温合金的发展历史和趋势.     

TiAl合金板材的制备及研究现状

本文综述了铸锭冶金和粉末冶金方法制备TiAl合金板材的工艺和国内外研究现状,介绍了铸轧技术、流延成形以及物理气相沉积等方法制备TiAl合金板材的工艺过程和材料性能,论述了上述方法的特点和发展趋势.     

TiAl金属间化合物工程实用化研究与进展

回顾了钢铁研究总院在提高TiAl金属间化合物合金可靠性和部件制备技术两方面的研究结果,介绍了己开展的应用研究及减重效果研究,并对TiAl合金今后的发展做了简要评述。     

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。     

TiAl基金属间化合物表面涂层研究进展

TiAl合金具有优异的高温力学性能,可以作为Ni基高温合金的轻量化替代材料,但氧化和磨损等行为限制了TiAl合金的高温服役时间,不利于工业化应用。通过在TiAl合金表面沉积涂层,可以使材料兼具基体的力学性能和涂层材料的表面性能,以提高TiAl合金适应不同服役环境的能力,进而拓展其应用范围。列举了TiAl合金使用的涂层材料应具有的性质;介绍了常见涂层的制备方法;以涂层成分分类,分别总结了不同涂层体系的研究现状,并展望了制备工艺和涂层性能的发展趋势。     

涡轮增压器压气叶轮爆裂转速数值分析与试验研究

随着内燃机不断向高效率、大功率、智能化方向发展,其核心部件涡轮增压器逐渐向高压比、高转速、大流量方向迈进。由于涡轮增压器压气叶轮的转速非常高,压气叶轮爆裂尤其是产生非包容性碎片时会对内燃机运行安全造成严重危害,甚至造成人员伤亡,因此研究涡轮增压器的包容性尤为重要。基于有限元法,针对涡轮增压器包容性(压气叶轮的爆裂转速和弱化方式),分别运用线弹性材料模型及双线性等向强化弹塑性材料模型模拟了涡轮增压器压气叶轮在离心载荷作用下的爆裂转速,并对完整压气叶轮及2种弱化处理的压气叶轮进行了包容性试验。结果表明:运用双线性等向强化弹塑性材料模型计算得到的压气叶轮爆裂转速与试验值约相差2%,而运用常规线弹性材料模型计算得到的压气叶轮爆裂转速与试验值约相差16%,偏保守。同时,2种弱化处理的压气叶轮均在预定转速下爆裂,验证了弱化方式的合理性与准确性;通过控制开槽的尺寸即可实现压气叶轮在预定转速下爆裂。研究结果为后续涡轮增压器压气叶轮包容性分析奠定了基础。     

TiAl基金属间化合物的发展

介绍了普通TiAl基金属间化合物的发展过程,特别是北京科技大学开发的高Nb-TiAl金属间化合物的成分-组织-性能-制备关系,Nb对TiAl合金相关系和抗氧化性的影响,Nb的强化机理和工程合金的制备和性能.最后简单总结了TiAl基金属间化合物的发展趋势.     

TiAl合金精密成形技术发展现状及展望

TiAl合金是一种优异的轻质耐高温结构材料,在航空、航天、汽车、兵器等热端部件制造领域具有广阔的应用和发展前景,但其较低的室温塑性、韧性和较差的冷/热加工性能,限制了其工程化的进程.为挖掘TiAl合金的应用潜力,国内外研究机构和企业从材料设计、组织性能调控到成形工艺等方面开展了卓有成效的研究.总结了近年来国内外在TiA...     

Recent research and development of mould materials for casting TiAl alloys

Intermetallic TiAl alloys are new generation high-temperature material. However, extensive application of TiAl alloys is hindered by some disadvantages, especially the high processing cost. Currently, precision casting is an effective method to manufacture TiAl components with complex shape. However, the interfacial reaction between the TiAl alloy melt and mould affects the quality of the castings and hinders extensive applications of casting TiAl components. In this paper, the research status of mould materials for the casting of TiAl alloys is reviewed. Performances of present used mould materials are compared in details. Reaction mechanisms between mould materials and the melts of TiAl alloys are also summarised. Finally, the future development tendency and prospect are pointed out.     

Investigation into the microstructure and mechanical properties of diffusion bonded TiAl alloys

TiAl alloys are potential candidates for replacing conventional Ti-alloys in gas turbine applications in the relatively lower temperature sections, owing to their low density and excellent high temperature properties. However, their intolerable ambient temperature brittleness hinders their use in such applications. Recently, TiAl alloys with some room temperature ductility were developed through alloy development programmes using special production routes such as powder metallurgy. However, the room temperature brittleness of these alloys could not be overcome. Sound joining of these alloys is a fundamental prerequisite for their successful integration into high temperature aerospace applications. It has been well demonstrated that diffusion bonding, a commonly used joining technology in conventional Ti-alloys, can successfully be used in joining of TiAl alloys both in as-cast or special-rolled conditions. In this study, diffusion bondability of a recently developed C containing TiAl alloy with a duplex microstructure using bonding parameters in the range of commercially available equipments was studied. Microstructural investigations in the joint area of the bonds were conducted to observe the presence of any weld defect. Additionally, the mechanical behaviour of the bonds was determined by shear testing to find out the optimum bonding parameters. Furthermore, the effect of post-bond heat treatment on the mechanical properties was investigated.     

航空发动机用先进高温钛合金材料技术研究与发展

新一代高推重比航空发动机压气机和涡轮系统高温环境使用的叶片、盘、机匣、整体叶盘和整体叶环等构件设计通常选用先进高温钛合金材料。本文综述近年来我国600℃高温钛合金、阻燃钛合金、TiAl合金、连续SiC纤维增强钛基复合材料及其应用技术取得的最新研究进展,并提出材料及构件设计、加工和使用亟待突破的关键技术,包括工业铸锭成分高纯化和均匀化控制技术、大规格棒材及特殊锻件制备技术、整体叶盘和整体叶环零件机械加工技术、材料性能评价及应用设计技术等。先进高温钛合金材料的不断应用将有力推动我国航空发动机技术发展。     

Using Turbocharger maps in gas exchange simulation and engine control units

Characterisation of turbocharger performance is important in gas exchange simulation and engine control unit calibration. Compressor and turbine performance maps are measured on a hot-gas test bed. As a result their performance maps have a large dependence on heat transfer. Gas exchange simulation software assumes adiabatic compressor and turbine maps. The direct use of measured maps leads to defective simulation results. The power balance of compressor and turbine in steady state operation leads to limited turbine performance maps. The acceleration of compressor and turbine are not covered in those maps. In gas exchange simulation the performance maps are extrapolated to cover the entire range of operation. Simulations using the extrapolated maps do not correlate with empirical results. This paper presents methods for reconciling results derived from maps with those observed in the real world over the same extrapolated operating range. The methods use existing maps without additional information to construct performance maps relevant for operation on internal combustion engines. A recipe approach for the application to measured maps is developed and applied to examples. Compared to mathematical extrapolation, the presented methods yield empirically sound extrapolations and improve the quality of gas exchange simulation results.     

数值模拟在整铸涡轮精密成形中的应用现状

随着计算方法和铸造工艺的发展,数值模拟技术在铸造领域中得到了广泛应用.涡轮作为发动机上的重要热端部件,其结构伴随着发动机的更新换代,向着精密化、轻量化、薄壁化方向发展,数值模拟技术也成为铸造工作者控制涡轮质量的重要手段.目前相关学者通过铸造模拟软件对涡轮精密成形的充型过程与宏观物理场结果进行分析,依据模拟结果来改善铸造...     

Joining of TiAl intermetallic by self-propagating high-temperature synthesis

This study reports on a novel approach for joining TiAl by self-propagating high-temperature synthesis (SHS). The Ti, Al and C powders were applied in the joining process with the assisted electromagnetic field. The microstructure analysis revealed that a dark TiAl₃ reaction layer existed at the interface. The TiC particles and multi-layer granular structures of the Ti–Al system were found in the reaction products. It was noted that the porosity was inevitable in direct SHS joining. In order to improve the joining quality, Ag-based brazing foil was inserted between the powder compacts and the TiAl substrate. Molten brazing alloy during SHS reaction improved the wettability of the interlayer to TiAl substrate and filled well into the holes in the reaction products. With the application of Ag-based brazing alloy, the density increased and the joining quality improved.     

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。     

Application of TiAl in a Turbocharger for Passenger Vehicles

Alloys based on γ‐TiAl phase (hereafter TiAl) can be thought of as intermediate between ceramics and heat‐resistant alloys. The greatest merit of TiAl is excellent high‐temperature strength in spite of its light weight (specific gravity of 4) while its chief disadvantage is brittleness. Accordingly, a rotating component in which applied stress is in proportion to weight is the most suitable application. Furthermore, in cases where weight reduction directly improves equipment performance, the disadvantage of TiAl should be compensated. This report describes the first commercial application of TiAl in a turbocharger for passenger vehicles.