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Advances in phase relationship for high Nb-containing TiAl alloys

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Rare Metals 2016年第1期35卷 15-25页

作者： yong-feng liang Xiang-Jun Xu Jun-Pin Lin State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Materials and Chemistry School Zhongyuan University of Technology

γ-TiAl alloys,including two categories（the conventional TiAl and the high Nb-containing TiAl（high Nb-TiAl））,are technologically intriguing because of their applications at high ***,the service temperature of the high Nb-TiAl alloys is 60-100℃higher than that of conventional TiAl *** developed TiAl alloys,for example TNB,TNM,β-γ alloys,belong to the high Nb-TiAl alloys,displaying similar behavior in phase transformation,strengthening,oxidation at high temperatures,and relationships between composition,microstructure,and mechanical *** work presents an in-depth review of the high Nb-TiAl alloys regarding the advances in phase diagram,formation mechanism of the new γ_1 phase,microsegregation induced by adding a high content of alloying element Nb,and the mechanism of the B2/ω phase *** challenges in developing the high Nb-TiAl alloys are also discussed.

关键词： TiAl alloy Nb addition Phase diagram Microsegregation Microstructure

Warm deformation behavior and work-softening mechanism of Fe- 6.5wt.%Si alloy

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Journal of Iron and Steel Research International 2020年第3期27卷 342-354页

作者： Xiang-ju Shi yong-feng liang Bin-bin Liu Bao Zhang feng Ye State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

Warm deformation behavior of the Fe-6.5wt.%Si alloy was studied by isothermal compression in the temperature range of 300-700℃.The results show that the influence of the ordered phases on the flow stress gradually weakens with increasing deformation *** flow stress of the furnace-cooled sample with the high degree of order at 300℃is higher than that of the quenched sample with the low degree of order,and the flow stresses of both samples are nearly the same at 500-700℃.The hardness difference between two samples deformed at 500℃gradually decreases with increasing strain,accompanying with a reduction in hardness of the furnace-cooled sample,which indicates a work-softening *** analyses of dislocation configurations and ordered structure suggest that the dynamic recovery and deformation-induced disorder result in the work-softening *** appropriate deformation temperature window for improving the formability of the Fe-6.5wt.%Si alloy is about 500-600℃.

关键词： Fe-6.5wt.%Si alloy Work softening Ordered structure Dynamic recovery Anti-phase boundary Dislocation

Mean First-Passage Time of an Asymmetric Kinetic Model Driven by Two Different Kinds of Colored Noises

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Communications in Theoretical Physics 2008年第3期49卷 689-695页

作者： LI Dong-Xi XU Wei GUO yong-feng WANG liang Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

The mean first-passage time （MFPT） of an asymmetric bistable system between multiplicative non-Gaussian noise and additive Gaussian white noise with nonzero cross-correlation time is investigated. Firstly, the non-Markov process is reduced to the Markov process through a path-integral approach; Secondly, the approximate Fokker Planck equation is obtained by applying the unified colored noise approximation and *** Theorem. The steady-state probability distribution （SPD） is also obtained. The basal functional analysis and simplification are employed to obtain the approximate expressions of MFPT T^±. The effects of the asymmetry parameter β, the non-Gaussian parameter （measures deviation from Gaussian character） r, the noise correlation times τ and τ2, the coupling coefficient A, the intensities D and a of noise on the MFPT are discussed. It is found that the asymmetry parameter β, the non-Gaussian parameter r and the coupling coefficient A can induce phase transition. Moreover, the main findings are that the effect of self-existent parameters （D, α, and τ） of noise and cross-correlation parameters （A, 7-2） between noises on MFPT T^± is different.

关键词： mean first-passage time asymmetric bistable system non-Gaussian noise Gaussian noise

Comprehensive impact of as-cast microstructure and ordered structures on formability of large-scale Fe-6.5 wt.%Si alloy ingots

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Journal of Iron and Steel Research International 2020年第2期27卷 180-187页

作者： Xiang-ju Shi yong-feng liang Shi-bo Wen Zhi-yi Ding Bao Zhang Wei Song feng Ye State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Large-scale Fe-6.5 wt.%Si ingot with excellent formability is required for a pilot line producing sheets through hot/cold *** variation of the as-cast microstructure,ordered structures and the formability of the Fe-6.5 wt.%Si alloy ingots with the cooling rate during casting was *** air-cooling condition,inhomogeneous microstructures with a low proportion of equiaxed grains were formed,but the formation of ordered structures was partially inhibited,especially *** microstructures with a high proportion of equiaxed grains were observed under the condition of furnace cooling,but the ordered structures were fully generated,and the degree of order is *** is generally believed that high degree of order is the main factor of brittleness,but the homogeneous microstructure(including grain morphology and size)of the furnace-cooled sample helps to improve the *** influence of these two aspects on formability is ***,the formability is tested through the flow stress during the compression and the microstructure after the *** results show that the furnace-cooled sample has better *** large-scale ingots,the control of as-cast microstructure becomes more significant than the control of degree of *** cooling during casting is important for the large-scale ingots to have good formability meeting the requirements of direct hot rolling.

关键词： Large-scale ingot Fe-6.5 wt.%Si alloy Cooling method Formability Ordered structure As-cast microstructure

Reaction behaviors occurring in Ti/Al foil metallurgy

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Rare Metals 2016年第1期35卷 100-105页

作者： Zheng-Zhang Shen Jun-Pin Lin yong-feng liang Lai-Qi Zhang Guo-Jian Hao State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

Reaction behaviors occurring in Ti/Al foil metallurgy were systematically *** emphasis was focused on the reaction between solid Al and Ti as well as subsequent reaction between TiAland Ti *** the solid reaction between Al and Ti,the presence of residual Al is mainly caused by inhomogeneous growth of TiAllayer and micro-voids existing at the ***,through reaction between molten Al and Ti,TiAl/Ti multilayer can be achieved with complete consumption of *** subsequent high-temperature heat treatment,TiAl/Ti multilayer will eventually turn into TiAl/TiAl multilayer accompanying with simultaneous formation and successive disappearance of intermediate phases,such as TiAland ***,it is found that the growth direction of TiAl layer changes as a function of annealing time between different couples in multi-intermetallics system.

关键词： Reaction behavior Foil metallurgy Multilayer TiAl3 TiAl

Chemical composition analysis on industrial scale ingots and castings of TiAl alloys

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China Foundry 2020年第6期17卷 441-446页

作者： Xian-fei Ding Yi-qun Zhao Jia-bin Zuo Xin feng Hai Nan yong-feng liang Yan-qing Su 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 BAIMTEC Material Co. Ltd.Beijing 100094China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology HarbinHarbin150001China

The chemical composition variation of the TiAl-4722 alloys was examined in a batch of the industrial scale master ingots,and in the corresponding castings prepared by conventional vacuum arc remelting(VAR)combined with induction skull melting(ISM)and investment casting *** content changes of major elements and interstitial elements were evaluated based on the chemical analysis at the top and bottom of the ingots and *** show that the contents of C,N,H,Fe and Si have almost no change in the ingots and castings,suggesting that the chemical analysis on these elements can be based on the batch *** O content keeps almost the same in different ingots,but exhibits relatively large differences in castings,which was probably influenced by the reaction between the shell mold and the molten alloy,and the spalling of face coat of the shell mold during *** the major elements of Al,Nb and Cr,the composition difference between the top and the bottom of the ingots is less than that of the *** for the O element,the trend is different,especially for the castings,suggesting that the investment casting is a homogenization process for Cr and Nb,but a differentiation process for *** contents of major elements in castings fluctuate mainly in the same range as that in the ingots,indicating that the contents of the major elements are controllable during investment casting.

关键词： TiAl alloys melting casting chemical composition casting ingot

Relationship between Maternal PBMC HBV cccDNA and HBV Serological Markers and its Effect on HBV Intrauterine Transmission

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Biomedical and Environmental Sciences 2019年第5期32卷 315-323页

作者： WANG Dan Dan YI Lin Zhu WU Li Na YANG Zhi Qing HAO Hai Yun SHI Xiao Hong WANG Bo feng Shu Ying feng yong liang WANG Su Ping Department of Epidemiology Shanxi Medical UniversityTaiyuan 030001ShanxiChina Department of Obstetrics and Gynaecology the Third People’s Hospital of Taiyuan CityTaiyuan 030001ShanxiChina

Objective To investigate the relationship between maternal peripheral blood mononuclear cells (PBMC) hepatitis B virus(HBV) covalenty closed circular deoxyribonucleic acid(cccDNA) and other HBV serological markers and its effects on HBV intrauterine transmission. Methods We enrolled 290 newborns and their hepatitis B surface antigen(HBsAg) positive mothers. HBV cccDNA in PBMC and HBV DNA in serum were detected by a real‐time PCR‐TaqM an probe while HBV serological markers were detected with an electrochemiluminescence immunoassay. Results There was a positive correlation between the levels of PBMC HBV cccD NA and serum HBV DNA and HBeA g(r = 0.436 and 0.403, P < 0.001). The detection rate of pattern A [‘HBsA g(+), HBeA g(+), and anti‐HBc(+)’] was significantly higher in the PBMC HBV cccD NA positive group than in the control group(χ^2 = 48.48, P < 0.001). There was a significant association between HBV intrauterine transmission and PBMC HBV cccD NA(χ^2 = 9.28, P = 0.002). In the presence of serum HBV DNA, HBeA g, and PBMC HBV cccD NA, the risk of HBV intrauterine transmission was three times higher(OR = 3.69, 95% CI: 1.30‐10.42) than that observed in their absence. The risk of HBV intrauterine transmission was the greatest(OR = 5.89, 95% CI: 2.35‐14.72) when both PBMC HBV cccD NA and pattern A were present. A Bayesian network model showed that maternal PBMC HBV cccD NA was directly related to HBV intrauterine transmission. Conclusion PBMC HBV cccDNA may be a direct risk factor for HBV intrauterine transmission. Our study suggests that serological markers could be combined with PBMC‐related markers in prenatal testing.

关键词： Hepatitis B virus Intrauterine transmission Peripheral blood mononuclear cells Covalently closed circular deoxyribonucleic acid Serological markers

Microstructures and phase transformation in directionally solidified TiAl-Nb alloys

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China Foundry 2020年第6期17卷 402-408页

作者： Fu-qiang Zhang Xian-fei Ding Hai Nan Ru-yue You Qiang Wang Jian-ping He Yan-qing Su yong-feng liang Jun-pin 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 AECC Hunan Aviation Powerplant Research Institute Harbin 150001China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyZhuzhou 412002China

Intermetallic Ti-45Al-8Nb-(W,B,Y)(at.%)and Ti-46Al-5Nb alloys are directionally solidified at a constant growth rate of 30μm·s-1 using a Bridgman type *** quenched microstructures and lengths of different phase regions were observed and measured after various growing times of 0-30 *** show that the phase transformations in different phase regions are mainly depending on the high temperature microstructure and the supercooling degree during quenching *** isothermal holding,the primary phase grows into the liquid phase,the dendrites change from equiaxed to columnar grains,and the length of the L+βphase region,L+β+αphase region and mushy zone varies,indicating that the entire directional solidification process can be described by a static equilibrium-nonequilibrium-dynamic equilibrium evolution *** addition,the gap between the original growth interface and front interface shows that the actual crystal growth rate is not equal to the drawing velocity during directional solidification.

关键词： TiAl alloys directional solidification quenched microstructure phase transformation

Laser Remelting of Plasma Sprayed NiCrAlY and NiCrAlY-Al_2O_3 Coatings

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Journal of Materials Science & Technology 2001年第5期17卷 525-528页

作者： Yingna WU, Gang ZHA NC, Bingchun ZHANG, Zhongchao feng and yong liang Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Fangjun LIU Key Laboratory for High Energy Density Beam Processing Technology, Beijing Aeronautical Manu Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

Two types of plasma sprayed coatings (NiCrAlY and NiCrAlY-A12O3) were remelted by a 5 kW cw CO2 laser. With increasing laser power and decreasing traverse speed in the ranges of 200-700 W and 5-30 mm/s respectively, the melted track grew in width and depth. In the optimum range of laser parameters, a homogeneous remelted layer without voids, cavities, unmelted particles and microcracks was formed. On the surface of remelted layers, Al203 and YAIO3 were detected. As a result of isothermal oxidation tests, weight gains of laser remelted coatings were obviously lower than that only plasma sprayed, especially laser remelted NiCrAlY-Al2O3 coatings. The effects of laser remelting and incorporation of A12O3 second phase in N1CrAlY matrix on high temperature oxidation resistance were discussed.

关键词： Ni Laser Remelting of Plasma Sprayed NiCrAlY and NiCrAlY-Al2O3 Coatings TBCS Al