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Research progress on refractory composition and deformability of shell molds for TiAl alloy castings

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China Foundry 2018年第1期15卷 1-10页

作者： Chun-ling Bao Shuang-qi Zhang Yu-yan Ren You-wei Zhang Hua-sheng Xie Jun Zhao titanium alloy Division Shenyang Research Institute of Foundry School of Materials Science and Engineering Shenyang University of Technology

At present, most TiAl components are produced by an investment casting process. Environmental and economic pressures have, however, resulted in a need for the industry to improve the current casting quality, reduce manufacturing costs and explore new markets for the process. Currently, the main problems for investment casting of TiAl alloys are cracks, porosities, and surface defects. To solve these problems, many studies have been conducted around the world, and it is found that casting defects can be reduced by improving composition and properties of the shell molds. It is important to make a summary for the related research progress for quality improvement of TiAl castings. So, the development on refractory composition of shell molds for TiAl alloy investment castings was reviewed, and research progress on deformability of shell mold for TiAl alloy castings both at home and abroad in recent years was introduced. The existing methods for deformability characterization and methods for improving the deformability of shell molds were summarized and discussed. The updated advancement in numerical simulation of TiAl alloy investment casting was presented, showing the necessity for considering the deformability of shell mold during simulation. Finally, possible research points for future studies on deformability of shell mold for TiAl alloy investment casting were proposed.

关键词： TiAl based alloys investment casting shell mold deformability

Forging-microstructure-tensile properties correlation in a new nearβhigh-strength titanium alloy

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Rare Metals 2021年第8期40卷 2109-2117页

作者： Huan Wang She-Wei Xin Yong-Qing Zhao Wei Zhou Wei-Dong Zeng State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China titanium alloy Research institute Northwest Institute for Nonferrous Metal ResearchXi’an710016China

Microstructures and tensile properties of a newβhigh-strength titanium alloy Ti-5321(Ti-5 Al-3 Mo-3 V-2 Zr-2 Cr-1 Nb-1 Fe)were investigated in this *** microstructures,including equiaxed microstructure(EM),bimodal microstructure(BM),basket-weave microstructure(WM)and lamellar microstructure(LM),were tailored by changing the forging process,and the influences of different microstructures on tensile properties were also *** results indicated that Ti-5321 exhibits a better combination of strength and ductility,compared to Ti-5553,Ti-1023,BT22 and *** ultimate tensile strength,total elongation and reduction in area could be achieved in a range of 1200-1300 MPa,10%-15%and40%-60%,*** influences of variant selection on the tensile properties in Ti-5321 alloy were also ***βforging and solution treatment,αphase maintained strictly Burgers orientation relation with adjacentβ*** features of the fractography in BM and LM were also explored to further explain the tensile properties and the fracture mode of Ti-5321 alloy.

关键词： New nearβtitanium alloy Forging process Variant selection Tensile properties

Improved Corrosion Resistance of Selective Laser Melted Ti–5Cu alloy Using Atomized Ti–5Cu Powder

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 1007-1014页

作者： Ying Han Hong-Rui Wang Yun-Dong Cao Wen-Tao Hou Shu-Jun Li School of Electrical Engineering Shenyang University of TechnologyShenyang 110870China titanium alloy Laboratory Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The different types of metal powder used for selective laser melting(SLM) process would cause distinct corrosion behavior due to the uniformity of the obtained *** SLM-produced Ti–5Cu alloy using atomized Ti–5Cu metal powder(SLMed Ti–5Cu) in this work reveals a relatively uniform microstructure with overwhelming acicular α/α′ phase and shows great advantages on corrosion resistance compared with the SLM-produced Ti–5Cu alloy using the mixture powder(SLMedM Ti–5Cu).The effect of the micro-galvanic cells decreases due to the undetectable Ti2Cu phase in the microstructure of the SLMed Ti–*** apparent passivation behavior was observed for SLMed Ti–5Cu instead of severe pitting phenomenon for the SLMed-M Ti–*** charge transfer resistance of SLMed Ti–5Cu in this work is 10.09 ± 2.63 MΩ cm2, which is significantly higher than that of SLMed-M Ti–5Cu(4.76 MΩ cm2).The above result indicates the atomized Ti–5Cu powder plays an important role in the formation of the uniform microstructure of SLMed product, thereby enhancing its corrosion resistance in Hank’s solution at 37 ℃.

关键词： Selective laser melting Corrosion behavior Uniform microstructure Ti-5Cu Passivation Polarization resistance

Numerical simulation for permanent mold centrifugal cast TiAl exhaust valve

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中国有色金属学会会刊：英文版 2005年第3期15卷 631-635页

作者：盛文斌李东 Department of Mechanical Engineering Shandong University of Technology Zibo 255049 China titanium alloy Laboratory Institute of Metal Research The Chinese Academay of Sciences Shenyang 110016 China

The filling and solidification in centrifugal field, as well as the forming mechanism of off-center porosities were summarized, based on the mathematical model established for the centrifugal cast TiAl exhaust valves. The calculated results show that the centrifugal field results in the phenomenon that the flow in the valve cavity consists of forward flow and backward flow. The unsymmetrical initial temperature field causes continuous unsymmetrical variation in the following solidification, which makes the final solidified region depart from the cavity axis and then leads to the occurrence of off-center porosity. A series of optimized parameters, including the entrance velocity of 0.6-1.3m/s, the rotation speed higher than 300r/min, 80mm or longer entrance length and 400℃ or higher preheated temperature of the mold, are suggested for the manufacture of permanent mold centrifugal cast TiAl exhaust valves.

关键词：钛铝合金排气阀金属型铸造数学模型

Effect of deformation processing parameter on microscopic structure of Ti14 alloy under semi-solid

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中国有色金属学会会刊：英文版 2007年第A1期17卷 504-508页

作者：郭萍赵永庆吴玮璐 titanium alloy Research Center Northwest Institute for Nonferrous Metal Research

Hot compressive deformation test of Ti-Al-Cu-Si alloy was performed on Gleeble-3500 hot-Simulator over the range of deformation temperature from 1 000 to 1 300 ℃,strain rate from 0.005 s-1 to 5 s-1,deformation degree from 40% to 70%,and samples of d 8 mm×15 mm were used. Change rules of microstructure were mainly studied. The results show that deformation temperature directly influences the nucleation growth and globurizing of grain,and with the temperature rising,the diameter of grain increases,the grain boundary widens. The effect of deformation degree on microstructure varies with deformation temperature. Equivalent diameter of grains shows a trend of falling before elevation with strain rate increasing and temperature rising.

关键词：钛合金半固体成型技术微观结构

Fatigue crack growth behaviors of a new burn-resistant highly-stabilized beta titanium alloy

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Rare Metals 2009年第6期28卷 545-549页

作者： WU Huana ZHAO Yongqing ZENG Weidong QIAN Li School of Materials Science and Engineering Northwestern Polytechnical University Xi ＇an 710072 China titanium alloy Research Center Northwest Institute for Nonferrous Metal Research Xi＇an 710016 China

This article presents the fatigue crack growth （FCG） behaviors of a new bum-resistant highly-stabilized beta Ti40 alloy. The FCG rates were analyzed. The fracture surfaces and the side surfaces of the test samples were explored. The results show that frequency affects the cracking behaviors of Ti40 alloy. Temperature also plays an important role in Ti40 alloy cracking. At room temperature （25℃）, when the frequency increases, the cracking rate changes a little in the range of low stress intensity factor （△K）, while it changes significantly when △K is high. At 500℃, the cracking rate of Ti40 alloy changes significantly during all the course of cracking. The fi＇equency also affects the microstructure patterns of Ti40 alloy. A number of secondary cracks appear in the area more than 200μm from the main crack at a high △K when the frequency is 1 Hz, but only a few secondary cracks exist when the frequency is 10 Hz. Facet image is the main image of the fracture surfaces when the frequency is 1 Hz. While, ductile striation occupies most of the area of fracture surfaces when the frequency is 10 Hz.

关键词： titanium alloys fatigue crack growth frequency temperature

Microstructure evolution and phase transformation of the mushy zone in a quenchedβ-solidifying TiAl alloy

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Journal of Materials Science & Technology 2024年第2期169卷 28-41页

作者： Fuqiang Zhang Xianfei Ding Leming Xu Xin Feng Hai Nan Jianping He Yongfeng Liang Junpin Lin State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Cast titanium alloy R&D Center Beijing Institute of Aeronautical MaterialsBeijing 100095China

This study investigates the phase constitutions and transformations that occur in the mushy zone and in the adjacent phase fields of a directionally solidified Ti-44Al-8Nb-1Cr alloy via quenching *** results indicate that the mushy zone consists of unmeltedβdendrites and interdendritic liquid,whose formation can be attributed to the difference in melting point aroused by local heterogeneity in ***βdendrite is composed of numerous subgrains with various *** quenching,theβdendrite transforms into Widmanstättenαvia a precipitation reaction,owing to the decreasing cooling rate caused by heat transfer from the surrounding ***,after quenching,the interdendritic liquid is transformed intoγ*** the singleβphase field and the lower part of the mushy zone,a massive transformation ofβtoγ***,in theβ+αphase field,bothβandαphases are retained to ambient *** the heating process,the transformation ofα→βgives rise to the formation ofβvariants,which affects the orientation ofβdendrites in the mushy *** growth kinematics of theα→βtransformation was elucidated,revealing the preferential growth directions of111and112forβ***,this study presents an illustration of the formation process of the mushy zone and the microstructural evolution during the heating and quenching process.

关键词： titanium aluminides Mushy zone Quenching Electron backscattering diffraction Phase transformation

Green, sustainable and massive synthesis of sodium vanadate nanowires toward industrialization

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Progress in Natural Science:Materials International 2023年第6期33卷 918-923页

作者： Wei Ni ANSTEEL Research institute of Vanadium & titanium (Iron & Steel) State Key Laboratory of Vanadium and titanium Resources Comprehensive Utilization

One-dimensional(1D) layered materials combine the advantages of layered materials and 1D nanomaterials,which has attracted intense interest not only in the academic research but also in the industrial *** sodium vanadate nanowires have received incremental attention due to the high capacity and enhanced electrical conductivity for promising advanced energy storage and conversion. However, the mass production of these 1D layered vanadium vanadates(1D NVO) are still of great challenge and the further scalable application in energy storage and conversion systems are hampered. Herein, we developed a facile, non-hydrothermal, green synthesis strategy for scalable, mass production of layered vanadium vanadate nanowires and their assemblies such as membranes, blocks, grains, powders toward industrial scale. It will pave a way for the industrial production of 1D inorganic materials and give a new insight into the fabrication of nanostructured materials beyond commercialized 1D/2D nanomaterials including carbon nanotubes(CNT) and layered double hydroxides(LDH).

关键词： Sodium vanadate nanowires Mass production Vanadium-based Barnesite 1D nanomaterials Self-assembly Nanowire membrane Green synthesis

Effects of heat treatments on microstructures of TiAl alloys

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International Journal of Minerals,Metallurgy and Materials 2022年第6期29卷 1225-1230页

作者： Wen Yu Jianxin Zhou Yajun Yin Zhixin Tu Xin Feng Hai Nan Junpin Lin Xianfei Ding State Key Laboratory of Materials Processing and Die and Mould Technology Huazhong University of Science and TechnologyWuhan 430074China Cast titanium alloy R&D Center Beijing Institute of Aeronautical MaterialsBeijing 100095China Beijing Engineering Research Center of Advanced titanium alloy Precision Forming Technology Beijing 100095China Beijing institute of Aeronautical Materials Co. Ltd.Beijing 100094China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

This study aims to investigate the effects of heat treatments on the microstructure ofγ-TiAl *** Ti-47Al-2Cr-2Nb alloy ingots were manufactured by casting method and then heat-treated in two types of heat *** microstructures were studied by both optical and scanning electron *** chemical compositions of two ingots were determined as *** ingot with lower Al content only obtains lamellar structures while the one higher in Al content obtains nearly lamellar and duplex structures after heat treatment within1270 to 1185℃.A small amount of B2 phase is found to be precipitated in both as-cast and heat-treated *** are distributed at grain boundaries when holding at a higher temperature,such as 1260℃.However,B2 phase is precipitated at grain boundaries and in colony interiors simultaneously after heat treatments happened at 1185℃.Furthermore,the effects of heat treatments on grain refinement and other microstructural parameters are discussed.

关键词： TiAl alloys microstructure heat treatment casting