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Grain refinement in a cast high Nb containing TiAl alloy by heat treatment
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作者 LIUZicheng LINJunpin WANGYanli LINZhi SONGXiping CHENGuoliang 《Rare Metals》 SCIE EI CAS CSCD 2004年第3期260-262,共3页
The grain refinement of an as-cast Ti-46Al-8.5Nb-0.2W (atom fraction in %)alloy by the cyclic heat treatments was studied. The heat treatment scheme included a tempering at1250℃ and cyclic tempering at 1000 and 1200... The grain refinement of an as-cast Ti-46Al-8.5Nb-0.2W (atom fraction in %)alloy by the cyclic heat treatments was studied. The heat treatment scheme included a tempering at1250℃ and cyclic tempering at 1000 and 1200℃ three times after solution treatment at thetemperature above α phase transus followed by immediate fan cooling. The fine and homogeneousnear-γ microstructure can be obtained by this heat treatment, which causes the breakdown of as-castmicro-structure and prevents the anomalous growing of original γ phase. 展开更多
关键词 γ-titanium-aluminide alloys grain refinement heat treatment Ti-46Al-8.5Nb-0.2W alloy microstructure
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Role of alloying and heat treatment on microstructure and mechanical properties of cast Al-Li alloys:A review
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作者 Guo-hua Wu You-jie Guo +4 位作者 Fang-zhou Qi Shen Zhang Yi-xiao Wang Xin Tong Liang Zhang 《China Foundry》 SCIE EI CAS CSCD 2024年第5期445-460,共16页
Due to the prominent advantages of low density,high elastic modulus,high specific strength and specific stiffness,cast Al-Li alloys are suitable metallic materials for manufacturing complex large-sized components and ... Due to the prominent advantages of low density,high elastic modulus,high specific strength and specific stiffness,cast Al-Li alloys are suitable metallic materials for manufacturing complex large-sized components and are ideal structural materials for aerospace,defense and military industries.On the basis of the microstructural characteristics of cast Al-Li alloys,exploring the role of alloying and micro-alloying can stabilize their dominant position and further expand their application scope.In this review,the development progress of cast Al-Li alloys was summarized comprehensively.According to the latest research highlights,the influence of alloying and heat treatment on the microstructure and mechanical properties was systematically analyzed.The potential methods to improve the alloy performance were concluded.In response to the practical engineering requirements of cast Al-Li alloys,the scientific challenges and future research directions were discussed and prospected. 展开更多
关键词 cast Al-Li alloy alloyING microstructure mechanical properties heat treatment
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Effects of heat treatments on microstructures of TiAl alloys
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作者 Wen Yu Jianxin Zhou +5 位作者 Yajun Yin Zhixin Tu Xin Feng Hai Nan Junpin Lin Xianfei Ding 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2022年第6期1225-1230,共6页
This study aims to investigate the effects of heat treatments on the microstructure ofγ-TiAl alloys.Two Ti-47Al-2Cr-2Nb alloy ingots were manufactured by casting method and then heat-treated in two types of heat trea... This study aims to investigate the effects of heat treatments on the microstructure ofγ-TiAl alloys.Two Ti-47Al-2Cr-2Nb alloy ingots were manufactured by casting method and then heat-treated in two types of heat treatments.Their microstructures were studied by both optical and scanning electron microscopies.The chemical compositions of two ingots were determined as well.The 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 microstructures.They 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. 展开更多
关键词 tial alloys microstructure heat treatment castING
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Microstructure Characteristics and Elevated Temperature Mechanical Properties of a B Containedβ-solidifiedγ-TiAl Alloy
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作者 王秀琦 GUO Ruiqi +5 位作者 刘国怀 LI Tianrui YANG Yuxuan CHEN Yang XIN Meiling WANG Zhaodong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第3期738-746,共9页
The improved microstructure and enhanced elevated temperature mechanical properties of Ti-44Al-5Nb-(Mo,V,B)alloys were obtained by vacuum arc re-melting(VAR)and primary annealing heat treatment(HT)of 1260℃/6 h/Furnac... The improved microstructure and enhanced elevated temperature mechanical properties of Ti-44Al-5Nb-(Mo,V,B)alloys were obtained by vacuum arc re-melting(VAR)and primary annealing heat treatment(HT)of 1260℃/6 h/Furnace cooling(FC).The phase transformation,microstructure evolution and tensile properties for as-cast and HTed alloys were investigated.Results indicate that three main phase transformation points are determined,T_(eut)=1164.3℃,T_(γsolv)=1268.3℃and T_(βtrans)=1382.8℃.There are coarse lamellar colonies(300μm in length)and neighbor reticular B2 andγgrain(3-5μm)in as-cast alloy,while lamellar colonies are markedly refined and multi-oriented(20-50μm)as well as the volume fraction and grain sizes of equiaxedγand B2 phases(about 15μm)significantly increase in as-HTed alloy.Phase transformations involvingα+γ→α+γ+β/B2 and discontinuousγcoarsening contribute to the above characteristics.Borides(1-3μm)act as nucleation sites forβ_(eutectic) and produce massiveβgrains with different orientations,thus effectively refining the lamellar colonies and forming homogeneous multi-phase microstructure.Tensile curves show both the alloys exhibit suitable performance at 800℃.As-cast alloy shows a higher ultimate tensile stress of 647 MPa,while a better total elongation of more than 41%is obtained for as-HTed alloy.The mechanical properties improvement is mainly attributed to fine,multi-oriented lamellar colonies,coordinated deformation of homogeneous multi-phase microstructure and borides within lamellar interface preventing crack propagation. 展开更多
关键词 tial alloy phase transformation heat treatment BORIDE microstructure mechanical properties
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Microstructure characteristics of Ti-43Al alloy during twin-roll strip casting and heat treatment 被引量:5
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作者 Mang XU Guo-huai LIU +2 位作者 Tian-rui LI Bing-xing WANG Zhao-dong WANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2019年第5期1017-1025,共9页
To shorten the fabrication process of difficult-to-form TiAl sheets, twin-roll strip casting and microstructural control were investigated in Ti-43Al alloy. A crack-free sheet with dimensions of 1000 mm × 110 mm ... To shorten the fabrication process of difficult-to-form TiAl sheets, twin-roll strip casting and microstructural control were investigated in Ti-43Al alloy. A crack-free sheet with dimensions of 1000 mm × 110 mm × 2 mm was obtained. The microstructure of stip casting sheets and heat treatments was systematically studied. The macrostructure consisted of columnar crystals extending inward and centrally located equiaxed crystals with severe Al segregation were observed along the thickness direction, due to the symmetrical solidification process and decreasing cooling rates. The strip casting alloy was characterized by fine duplex microstructure with a grain spacing of 20-30 μm and a lamellar spacing of 10-20 nm. Furthermore, multiple microstructures of near gamma, nearly lamellar and fully lamellar were obtained through heat treatment process with significantly improved homogeneity of the microstructure. 展开更多
关键词 strip casting tial alloy sheet fabrication microstructure characterization heat treatment
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Effects of heat treatment on microstructure of directionally solidified Ti-45Al-8Nb-(W,B,Y) alloy 被引量:2
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作者 丁贤飞 林均品 +1 位作者 张来启 陈国良 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第1期26-31,共6页
The effects of heat treatments on typical microstructures of directionally solidified(DS) Ti-45Al-8Nb-(W,B,Y)(molar fraction,%) alloys prepared by the Bridgeman method were studied.Two typical DS microstructures... The effects of heat treatments on typical microstructures of directionally solidified(DS) Ti-45Al-8Nb-(W,B,Y)(molar fraction,%) alloys prepared by the Bridgeman method were studied.Two typical DS microstructures including full lamellae with cellular growth morphology and massive structure with dendritic growth morphology were examined.The results show that the heat treatment of 1250 ℃ for 24 h + 900 ℃ for 30 min+air cooling can efficiently eliminate the B2 phase in the DS alloys and change the massive structure of the rapid DS alloy into lamellar microstructure.Columnar lamellar colonies with widths of 150-200 μm and 50-100 μm respectively were observed in intercellular and dendritic arm regions.The heat treatment of 1 400 ℃ for 12 h+900 ℃ for 30 min+air cooling could simultaneously remove the B2 phase,massive structure and solidification segregations from the DS alloys,however,it caused severe growth of grains. 展开更多
关键词 tial alloy directional solidification heat treatment microstructure SEGREGATION
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Homogenization treatment of high Nb containing TiAl alloys with as-cast and as-forged microstructures 被引量:4
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作者 XU Zhengfang XU Xiangjun LIN Junpin ZHANG Yong WANG Yanli LIN Zhi CHEN Guoliang 《Rare Metals》 SCIE EI CAS CSCD 2008年第2期181-186,共6页
The effect of heat treatment on the microstructure evolution of a high Nb containing TiAl alloy has been studied. The results indicate that β-segregation, β-segregation and S-segregation in the as-cast and as-forged... The effect of heat treatment on the microstructure evolution of a high Nb containing TiAl alloy has been studied. The results indicate that β-segregation, β-segregation and S-segregation in the as-cast and as-forged alloys can be effectively eliminated at the temperature above Tα (1350-1400℃) for long holding time (12-24 h) and the full lamellar (FL) microstructure is gained. For the two alloys, the lamellar colony sizes are 120 μm and 2000 μm, respectively after heat treatment at 1400℃ for 12 h. Meanwhile, the sizes are 210 μm and 3000 μm, respectively at 1350℃ for 24 h. To get a fine homogenous microstructure, the primary as-cast alloy is first subjected to preheat treatment for eliminating the segregations. After the preheat treatment, the ailoy is processed by the multi-step canned forging to attain the microstructure with fine grain size. 展开更多
关键词 tial-based alloy Nb-containing FL microstructure heat treatment rnicrosegregation
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Synergistic effects of composition and heat treatment on microstructure and properties of vacuum die cast Al-Si-Mg-Mn alloys 被引量:3
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作者 Jun-jie Xu Ye Pan +1 位作者 Tao Lu Bing Bo 《China Foundry》 SCIE 2018年第2期117-123,共7页
The purpose of this study was to prepare high-quality Al-Si-Mg-Mn alloy with a good combination of strength and ductility employing the vacuum-assisted high-pressure die cast process. An orthogonal study of heat treat... The purpose of this study was to prepare high-quality Al-Si-Mg-Mn alloy with a good combination of strength and ductility employing the vacuum-assisted high-pressure die cast process. An orthogonal study of heat treatments was conducted to design an optimized T6 heat treatment process for both Al-10%Si-0.3%Mg-Mn and Al-11%Si-0.6%Mg-Mn alloys. The results demonstrate that no obvious blisters and warpage were observed in these two alloys with solid solution treatment. After the optimal T6 heat treatment of 530°C×3 h + 165°C×6 h, Al-11%Si-0.6%Mg-Mn alloy has better mechanical properties, of which tensile strength, yield strength and elongation reached 377.3 MPa, 307.8 MPa and 9%, respectively. The improvement of mechanical properties can be attributed to the high density of needle-like β″(Mg_5Si_6) precipitation after aging treatment and the fine and spherical eutectic Si particles uniformly distributed in the α-Al matrix. 展开更多
关键词 heat treatment vacuum die casting Al-Si-Mg-Mn alloy microstructure mechanical properties
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Effect of heat treatment on microstructure and tensile properties of A356 alloys 被引量:27
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作者 彭继华 唐小龙 +1 位作者 何健亭 许德英 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第9期1950-1956,共7页
Two heat treatments of A356 alloys with combined addition of rare earth and strontium were conducted.T6 treatment is a long time treatment(solution at 535 ℃ for 4 h + aging at 150 ℃ for 15 h).The other treatment ... Two heat treatments of A356 alloys with combined addition of rare earth and strontium were conducted.T6 treatment is a long time treatment(solution at 535 ℃ for 4 h + aging at 150 ℃ for 15 h).The other treatment is a short time treatment(solution at 550 ℃ for 2 h + aging at 170 ℃ for 2 h).The effects of heat treatment on microstructure and tensile properties of the Al-7%Si-0.3%Mg alloys were investigated by optical microscopy,scanning electronic microscopy and tension test.It is found that a 2 h solution at 550 ℃ is sufficient to make homogenization and saturation of magnesium and silicon in α(Al) phase,spheroid of eutectic Si phase.Followed by solution,a 2 h artificial aging at 170 ℃ is almost enough to produce hardening precipitates.Those samples treated with T6 achieve the maximum tensile strength and fracture elongation.With short time treatment(ST),samples can reach 90% of the maximum yield strength,95% of the maximum strength,and 80% of the maximum elongation. 展开更多
关键词 Al-Si casting alloys heat treatment tensile property microstructural evolution
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Microstructural evolution of Mg9AlZnY alloy with vibration in lost foam casting during semi-solid isothermal heat treatment 被引量:4
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作者 赵忠 樊自田 +1 位作者 蒋文明 董选普 《中国有色金属学会会刊:英文版》 CSCD 2010年第S3期768-773,共6页
The nearly equiaxed grains of Mg9AlZnY alloy were obtained by vibrating solidification in lost foam casting(LFC) and the microstructure of Mg9AlZnY alloy was analyzed.On this basis,the morphology and size of α-Mg gra... The nearly equiaxed grains of Mg9AlZnY alloy were obtained by vibrating solidification in lost foam casting(LFC) and the microstructure of Mg9AlZnY alloy was analyzed.On this basis,the morphology and size of α-Mg grains fabricated by semi-solid isothermal heat treatment(SSIT) at 530 ℃ and 570 ℃ holding different time were studied.The results show that the main constituent phases of Mg9AlZnY alloy are α-Mg,β-Mg17Al12 and Al2Y,and the Y can greatly refine α-Mg grains.The distribution of α-Mg grains equivalent diameters between 20 and 100 μm is up to 87%,and the average roundness of α-Mg grains reaches 1.37 in the specimen obtained at 570 ℃ and holding time 60 min.According to the analysis of solidification kinetics and thermodynamic,binary eutectic with low melting point melts firstly on SSIT process.As the liquid fraction increases with the solute diffusibility,both of the shape and size of α-Mg grains change ceaselessly.When the liquid fraction reaches equilibrium,the α-Mg grains are gradually spheroidized under the interfacial tension,and then the α-Mg grains begin to combine and grow.Evolution of α-Mg dendritic grains on SSIT process is obviously different from that of equiaxed grains. 展开更多
关键词 LOST foam casting(LFC) SEMI-SOLID ISOTHERMAL heat treatment(SSIT) MICROSTRUCTURAL evolution magnesium alloy
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A NEW HEAT TREATMENT PROCESSING FOR TiAl BASED ALLOY 被引量:1
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作者 He Yuehui Huang Baiyun +1 位作者 Liu Yong Liu Yexiang(Research Institute ofpowder Metallurgy Central South University of Technology, Changsha 410083) 《中国有色金属学会会刊:英文版》 CSCD 1996年第3期96-102,共7页
ANEWHEATTREATMENTPROCESSINGFORTiAlBASEDALLOY¥HeYuehui;HuangBaiyun;LiuYong;LiuYexiang(ResearchInstituteofpowd... ANEWHEATTREATMENTPROCESSINGFORTiAlBASEDALLOY¥HeYuehui;HuangBaiyun;LiuYong;LiuYexiang(ResearchInstituteofpowderMetallurgyCentr... 展开更多
关键词 tial based alloy microstructure MECHANICAL PROPERTY heat treatment
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Microstructural evolution of a forged TiAl based alloy during heat treatment at subtransus temperature
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作者 唐建成 黄伯云 +1 位作者 刘文胜 贺跃辉 《中国有色金属学会会刊:英文版》 CSCD 2000年第2期183-186,共4页
Microstructural evolution of a forged TiAl based alloy during heat treatment from 1 180 ℃ to 1 300 ℃ was investigated. The grain sizes of the alpha phases as well as the sizes and the volume fractions of the gamma p... Microstructural evolution of a forged TiAl based alloy during heat treatment from 1 180 ℃ to 1 300 ℃ was investigated. The grain sizes of the alpha phases as well as the sizes and the volume fractions of the gamma phases were evaluated as a function of heat treatment temperature and time. When the alloys are isothermally heat treated at subtransus temperatures, the sizes of gamma phases(D γ) increase slightly with heat treatment temperature and time and those of alpha phases(D α) and the volume fractions of gamma phases(φ γ) vary significantly with holding time in the early stages of heat treatments, but after heat treatments for 2 h, φ γ reveal little variations with holding times and D α approach limits, which can be described by D α0 =0.65D γ/φ γ. Besides, it has been found that the alpha phases in the specimens heat treated at 1 260 ℃ and 1 300 ℃ contain lamellar structures, at low temperatures, however, appear featureless. 展开更多
关键词 tial BASE alloy heat treatment microstructure
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Role of heat treatment in the improvement of mechanical properties of a high-quality Al-11Si-1.5Cu-0.3Mg casting alloy
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作者 Tao Lu Ji-li Wu +2 位作者 Ye Pan Shi-wen Tao Yu Chen 《China Foundry》 SCIE CAS 2015年第2期111-117,共7页
The purpose of this study is to prepare a high-quality Al-11Si-1.5Cu-0.3Mg casting al oy with a good combination of strength and ductility. The microstructures of as-cast al oy were tailored by employing combined addi... The purpose of this study is to prepare a high-quality Al-11Si-1.5Cu-0.3Mg casting al oy with a good combination of strength and ductility. The microstructures of as-cast al oy were tailored by employing combined additives of Al-3wt.%B reifner, Al-10wt.%Sr modiifer and trace addition of La element. By using OM and SEM, the characteristics of the morphologies of eutectic Si particles and the fracture surfaces of the al oys after solution treatment and aging treatment were measured. The mechanical properties of the al oys after single-step or two-step solution treatment were investigated by tensile testing, and the quality of casting samples were evaluated by quality index, Q. The results indicate that the al oy with substantial y modiifed microstructures displays an improvement in mechanical properties of 270 MPa in ultimate tensile strength and 6% in elongation. After an optimized two-step solution treatment of 490oC/4h+505oC/4h, the ultimate tensile strength and elongation can reach 346 MPa and 10%, respectively. Under the aging condition, the elongation maintains a relative high value of 5%together with the strength of about 400 MPa, which is the outstanding combination of strength and ductility. 展开更多
关键词 aluminum alloys castING microstructure heat treatment mechanical properties
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A new post-weld heat treatment to improve toughness of 9Cr-1Mo steel weld metals
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作者 王红鸿 雷玄威 吴开明 《China Welding》 EI CAS 2013年第3期31-35,共5页
9Cr-1Mo ferritic steels have been used in the conventional power generation plants due to their excellent creep resistance. However, one of the main obstacles in welding 9Cr-1Mo steels is the formation of undesirable ... 9Cr-1Mo ferritic steels have been used in the conventional power generation plants due to their excellent creep resistance. However, one of the main obstacles in welding 9Cr-1Mo steels is the formation of undesirable coarse columnar grains in weld metal whieh ean severely compromise the toughness. A new post-weld heat treatment (PWHT) is developed in the present work. Unlike the conventional processes in which the post-weld heat treatment is carried out below Ac1 , the use of temperatures above the Ac1 of 9Cr-1Mo alloy is considered. The new PWHT at a temperature above Ac1 improves the toughness of 9Cr-1Mo weld metals effectively. The improvement in toughness is mainly due to refinement and homogenization of mierostruetures. Key words 展开更多
关键词 metal and alloys WELDING microstructure grain refinement post-weld heat treatment
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Microstructure evolution of Ti–46Al–6Nb–(Si,B) alloys during heat treatment with W addition 被引量:2
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作者 Shou-Zhen Cao Shu-Long Xiao +5 位作者 Yu-Yong Chen Jing Tian Li-Juan Xu Xiao-Peng Wang Jian-Chao Han Yi Jia 《Rare Metals》 SCIE EI CAS CSCD 2016年第1期85-92,共8页
The cast ingots of Ti-46Al-6Nb-0.25Si-0.2B and Ti-46Al-6Nb-0.5W-0.25Si-0.2B(at%) were made by induction skull melting(ISM) technique.A series of heat treatments(HTs) were conducted to research the microstructure... The cast ingots of Ti-46Al-6Nb-0.25Si-0.2B and Ti-46Al-6Nb-0.5W-0.25Si-0.2B(at%) were made by induction skull melting(ISM) technique.A series of heat treatments(HTs) were conducted to research the microstructure evolution of both alloys.Microstructure and tensile property were examined by scanning electron microscope(SEM),X-ray diffraction(XRD),transmission electron microscope(TEM),and tensile testing machine.The results show that microsegregation(liquid segregation and solid segregation) is exacerbated by the addition of0.5 at%W;the addition of Nb,W in TiAl alloy makes the phase transition difficultly take place;then,the microstructures and tensile properties of both alloys are improved after certain HT processes;finally,the thicknesses of the γ/α_2 lamellae after a certain HT process are significantly affected by the number of residual γ phases before the furnace-cooling moment. 展开更多
关键词 tial alloy heat treatment W addition microstructure evolution MICROSEGREGATION
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Effects of grain refining and modification on mechanical properties and microstructures of Al-7.5Si-4Cu cast alloy 被引量:2
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作者 刘光磊 司乃潮 +1 位作者 孙少纯 吴勤方 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期946-953,共8页
Al-7.5Si-4Cu cast alloy melt modified by Al-5Ti-B, RE and Al-10Sr master alloys were poured in the chromite sand moulds, to investigate comparatively the effects of individual or combined additions of grain refiners a... Al-7.5Si-4Cu cast alloy melt modified by Al-5Ti-B, RE and Al-10Sr master alloys were poured in the chromite sand moulds, to investigate comparatively the effects of individual or combined additions of grain refiners and modifiers on the mechanical properties, microstructures, grain refining and modification, and intermetallic compounds of the alloy. The results show that the mechanical properties and the microstructures of Al-7.5Si-4Cu cast alloys are improved immensely by combining addition of 0.8%Al-5Ti-B, 0.1%RE and 0.1%Al-10Sr grain refiners and modifiers compared with the individual addition and cast conditions. For individual addition condition, addition of 0.8%Al-5Ti-B master alloy can obtain superior tensile strength, Brinell hardness and finer equiaxedα(Al) dendrites. The alloy with 0.1%RE master alloy shows the highest improvement in ductility because the rare earth can purify the molten metal and change the shape of intermetallic compounds. While the alloy with 0.1%Al-10Sr modifier shows only good improvement in yield strength, and the improvement of other performance is unsatisfactory. The Al-10Sr modifier has a significant metamorphism for the eutectic silicon, but will make the gas content in the aluminum alloy melt increase to form serious columnar grain structures. The effects of grain refining and modification on mean area and aspect ratio have the same conclusions obtained in the mechanical properties and the microstructures analyses. 展开更多
关键词 Al-7.5Si-4Cu cast alloy grain refinement modification treatment mechanical properties microstructureS
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TiAl合金铸件的热处理组织调控机制
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作者 余稳 徐永东 +7 位作者 朱秀荣 王俊升 刘辰 付玉 王荫洋 李雷 韩俊刚 王宇 《航空制造技术》 CSCD 北大核心 2024年第14期51-58,共8页
TiAl合金铸态组织粗大,致使其铸件强度低、塑性差,必须通过热处理细化铸态组织。利用OM和SEM研究了Ti-47Al-2Cr-2Nb合金铸件不同热处理组织演变规律,优化制定了双态和近片层组织热处理工艺,实现了晶粒细化,揭示了细化机理。结果表明,118... TiAl合金铸态组织粗大,致使其铸件强度低、塑性差,必须通过热处理细化铸态组织。利用OM和SEM研究了Ti-47Al-2Cr-2Nb合金铸件不同热处理组织演变规律,优化制定了双态和近片层组织热处理工艺,实现了晶粒细化,揭示了细化机理。结果表明,1185℃/6 h/炉冷双态组织热处理和1185℃/6 h/炉冷+1330℃/0.25 h/炉冷近片层组织热处理可分别将铸态组织晶粒尺寸细化75.51%和40.21%。双态组织热处理晶粒细化机制是在片层团晶粒内部析出大量γ晶粒打断原始粗大的片层团晶粒,γ晶核在片层团晶粒内形核来源于Al元素偏析和γ片层连续粗化。近片层组织热处理晶粒细化机制是在α单相区短时保温时发生了γ→α转变,破坏了原始粗大的片层团晶粒。等轴γ晶粒对α晶粒长大有钉扎作用,使得冷却后形成的片层团晶粒尺寸较小。 展开更多
关键词 tial合金铸件 热处理 双态组织 近片层组织 晶粒细化
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Effect of Si-addition as a grain refiner on microstructure and properties of Ti-6Al-4V Alloy 被引量:2
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作者 Khaled M.IBRAHIM Abdel Hamied HUSSEIN Mohamed ABDELKAWY 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第7期1863-1874,共12页
Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V... Two different Ti alloys were cast in a graphite mould using vacuum induction skull melting furnace. The first alloy was Ti-6Al-4V and the second was Ti-6Al-4V 0.5Si. Silicon as a grain refiner was added into Ti-6Al-4V alloy, and the effects of Si-addition on the microstructure and properties of the as-cast and swaged alloys were investigated. Hot swaging at 900 °C was performed on the cast samples and then two different thermal treatments were applied. The first treatment was done by heating the swaged samples at 1050 °C to produce fine lamella structure, while the second treatment was carried out at 1050 °C and then decreased the temperature to 800 °C for getting coarse lamella structure. An addition of 0.5% Si to Ti-6Al-4V alloy decreased the grain size of the as-cast sample from 627 to 337 μm. There was an increase in ultimate tensile strength of about 25 MPa for the as-cast Ti-6Al-4V 0.5Si alloy compared to Ti-6Al-4V due to the refinement effect caused by Si addition. A maximum ultimate tensile strength of 1380 MPa and a minimum corrosion rate (1.35×10 6 mm/a in Hank’s solution and 5.78×10 4 mm/a in NaCl solution) were reported for the heat treated fine lamella structure of Ti-6Al-4V 0.5Si alloy. The wear rate was decreased to about 50% by adding 0.5% Si at low sliding speeds and to about 73% at high sliding speeds. 展开更多
关键词 Ti-6Al-4V alloy silicon castING grain refinement heat treatment wear
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EFFECT OF HEAT TREATMENT ON INTERMEDIATE TEMPERATURE STRESS RUPTURE PROPERTIES OF ALLOY K403 被引量:1
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作者 Zheng Yunrong, Li Shuyuan, Ma Shuwei (Beijing Institute of Aeronautical Materials, Beijing, 100095, China) 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1997年第4期64-69,共6页
The standard heat treatment of cast nickel base superalloy K403 is the solid solution treatment of 1210℃/4h, air cooling. It is very difficult to meet the requirements of Aviation Standard HB5155, in which the stre... The standard heat treatment of cast nickel base superalloy K403 is the solid solution treatment of 1210℃/4h, air cooling. It is very difficult to meet the requirements of Aviation Standard HB5155, in which the stress rupture life at 750℃ and 645MPa is longer than 50h. The results showed that the intermediate temperature stress rupture properties impaired by treatment of 1210℃/4h were due to precipitation of too small γ′ phase(<0.2μm) in grains and absence of the secondary carbides at grain boundaries. Microstructure containing the intergranular M6C carbides with envelope of γ′ and the residual coarse γ′ was obtained by means of 1180℃/4h treatment, therefore the stress rupture life was obviously increased to meet the demand of HB5155. The effect of γ′ size was also discussed from the view point of deformation mechanism in this paper. 展开更多
关键词 cast alloys heat resistant alloys heat treatment microstructure intermediate temperature stress rupture properties deformation mechanism
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850℃等温时效对高Nb-TiAl合金组织和力学性能的影响
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作者 李莹 李栋 +2 位作者 常辉 樊江磊 王永彪 《热加工工艺》 北大核心 2024年第16期35-38,共4页
采用光学显微镜、扫描电子显微镜、X射线衍射仪和显微硬度仪等手段,系统研究了850℃等温时效对高Nb-TiAl合金的显微组织及硬度的影响。结果表明:锻态高Nb-TiAl合金显微组织为近片层组织结构,片层团尺寸约为112μm,片层间距约为1.6μm,... 采用光学显微镜、扫描电子显微镜、X射线衍射仪和显微硬度仪等手段,系统研究了850℃等温时效对高Nb-TiAl合金的显微组织及硬度的影响。结果表明:锻态高Nb-TiAl合金显微组织为近片层组织结构,片层团尺寸约为112μm,片层间距约为1.6μm,具有锯齿状晶界,主要由γ和α2相组成;合金在850℃等温时效分别为5 min、5 h、10 h、20 h的过程中,其显微组织主要由γ相、α2相和少量β相形成的片层组织结构组成,随着等温时间的延长,合金片层团和片层间距均存在明显的粗化现象;在不同的等温时效过程中,合金的表面皆表现出比较高的硬度值(420~460 HV),其显微硬度随保温时间的延长呈下降趋势。 展开更多
关键词 高Nb-tial合金 热处理 微观组织 显微硬度
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