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Rejuvenation Heat Treatment of the Second-Generation Single-Crystal Superalloy DD6

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Acta Metallurgica Sinica(English Letters) 2015年第10期28卷 1278-1285页

作者： zhen-Xue shi shi-Zhong Liu Jia-Rong Li Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The second-generation single-crystal superalloy DD6 with [001] orientation was prepared by screw selecting method in the directionally solidified furnace. The long-term aging of the alloy after full heat treatment was performed at1100 °C for 400 h. Then the rejuvenation heat treatment 1300 °C/4 h/AC ？ 1120 °C/4 h/AC ？ 870 °C/24 h/AC was carried out. The stress rupture properties were investigated at 760 °C/800 MPa, 850 °C/550 MPa, 980 °C/250 MPa and1100 °C/140 MPa after different heat treatments. The microstructures of the alloy at different conditions were studied by SEM. The results show that c0 phase of the alloy became very irregular and larger after long-term aging at 1100 °C for 400 h. A very small amount of needle-shaped TCP phase precipitated in the dendrite core. The coarsened c0 phase and TCP phase dissolved entirely after rejuvenation heat treatment. The microstructure was restored and almost same with the original microstructure. The stress rupture life of the alloy decreased in different degrees at various test conditions after long-term aging. The stress rupture life of the alloy after rejuvenation heat treatment all restores to the original specimen more than 80%at different conditions. The microstructure degradation of the alloy during long-term aging includes coarsening of the c0 phase,P-type raft and precipitation of TCP phase, which results in the degeneration of stress rupture property. The rejuvenation heat treatment succeeds in restoring the original microstructure and stress rupture properties of the alloy.

关键词： Single-crystal superalioy DD6 Rejuvenation heat treatment Stress rupture properties

Is ABP1 an Auxin Receptor Yet？

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Molecular Plant 2011年第4期4卷 635-640页

作者： Jing-Hua shi zhen-Biao Yang Center for Plant Cell Biology Department of Botany and Plant Sciences University of California Riverside CA 92521 USA

AUXIN BINDING PROTEIN 1 （ABP1） has long been proposed as an auxin receptor to regulate cell expansion. The embryo lethality of ABP1-null mutants demonstrates its fundamental role in plant development, but also hinders investigation of its involvement in post-embryonic processes and its mode of action. By taking advantage of weak alleles and inducible systems, several recent studies have revealed a role for ABP1 in organ development, cell polarization, and shape formation. In addition to its role in the regulation of auxin-induced gene expression, ABP1 has now been shown to modulate non-transcriptional auxin responses. ABP1 is required for activating two antagonizing ROP GTPase signaling pathways involved in cytoskeletal reorganization and cell shape formation, and participates in the regulation of clathrinmediated endocytosis to subsequently affect PIN protein distribution. These exciting discoveries provide indisputable evidence for the auxin-induced signaling pathways that are downstream of ABP1 function, and suggest intriguing mechanisms for ABPl-mediated polar cell expansion and spatial coordination in response to auxin.

关键词： Hormonal regulation hormone biology receptors signal transduction cell signaling.

Effects of Heat Treatment on Surface Recrystallization and Stress Rupture Properties of a Fourth-Generation Single-Crystal Superalloy after Grit Blasting

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Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 614-620页

作者： zhen-Xue shi shi-Zhong Liu Xiao-Guang Wang Jia-Rong Li Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials Beijing 100095 China

The specimens of a fourth-generation single-crystal superalloy were grit-blasted and heat-treated in vacuum at 1100, 1150, 1200, 1250 and 1300 °C for 4 h, respectively. Then, the microstructure and the stress rupture properties of the recrystallized alloy were investigated at 1150 °C/120 MPa. The results showed that a cellular recrystallization occurred in the surface layer after heating at 1100, 1150 and 1200 °C for 4 h. An equiaxed recrystallization formed as the specimen was heat-treated at 1300 °C for 4 h, while a mixed recrystallization occurred in the specimen heat-treated at 1250 °C for 4 h. The recrystallized depth clearly increased with a rise of the heat treatment temperature. The stress rupture life continuously decreased with a rise of the heat treatment temperature up to 1250 °C. Although the overall stress rupture life reduced to different degrees, the stress rupture life of specimen after heat treatment at 1300 °C was relatively high and intermediate between those of specimens treated at 1150 and 1200 °C. The fact that the stress rupture life reduced to different degrees after heat treatment can be attributed to the recrystallization of the surface layer and to the microstructure evolution of the interior of the specimen. The small γ’ phase precipitated again after heat treatment at 1300 °C for 4 h. So,the stress rupture life was relatively longer than that after heat treatment at 1200 or 1250 °C although the equiaxed recrystallization formed in the surface layer.

关键词： Single-crystal superalloy Heat treatment Recrystallization Stress rupture properties

Microstructures and grain refinement performance of Al-Ti-B-C grain refiner via powder metallurgy

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Rare Metals 2022年第7期41卷 2357-2362页

作者： Cong Xu Wen-Long Xiao shi-zhen Wen Yue-Jun zhen Chao-Li Ma Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education School of Material Science and EngineeringBeihang UniversityBeijing 100191China Lizhong Group Baoding Lizhong Wheel Manufacturing Co.Ltd.Baoding 071000China

The Al-5Ti-0.5B-0.5C grain refiner was pre-pared by powder metallurgy(PM).Microstructures of the grain refiner and its grain refinement performance in commercially pure aluminum(Al)were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),and differential scanning calorimetry(DSC).It is found that the average grain size of commercially pure Al can be reduced from~15,000 to~180μm by the addition of Al-5Ti-0.5B-0.5C grain refiner prepared by PM,based on 0.01 wt%Ti *** grain refinement efficiency begins to decrease slightly when the grain refiner is kept in the melt for 60 *** grain refinement is attributed to high stability,proper size,and high density of Al3Ti,TiB2,and TiC particles.

关键词： Al–Ti–B–C Powder metallurgy Microstructure Grain refinement

Effect of Hf on Stress Rupture Properties of DD6 Single Crystal Superalloy After Long Term Aging

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Journal of Iron and Steel Research International 2012年第7期19卷 66-70页

作者： shi zhen-xue LI Jia-rong LIU shi-zhong National Key Laboratory of Science and Technology on Advanced High Temperature Structural Materials Beijing Institute of Aeronautical Materials Beijing 100095China

The specimens of the second generation single crystal superalloy DD6 with different Hf contents were prepared in the directionally solidified furnace with a high temperature gradient. The long term aging of the specimens after full heat treatment was performed at 1040℃for 800 h. The effect of Hf on the microstructure and stress rupture properties under 980℃/250 MPa of the alloy after long term aging was investigated. The results show that the γ＇ coarsening and rafting and no topologically close packed phase （TCP） are observed in the microstructures of DD6 alloy with different Hf contents after aged at 1 040℃ for 800 h. It indicates that DD6 alloy with different Hf contents all possesses good microstructure stability. With increasing Hf content the rupture life after long term aging turns shorter and the elongation represents the increasing first and decreasing afterwards. The fracture mechanism of the alloy with different Hf contents at 980℃/250 MPa all shows dimple model. The influence of the microstructures on the stress rupture properties of the alloy is also discussed.

关键词： DD6 single crystal superalloy stress rupture property long term aging

Nonlocal Symmetries and Conservation Laws of Nonlocal Camassa-Holm Type Equations

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Acta Mathematicae Applicatae Sinica 2015年第4期31卷 909-920页

作者： zhen-hua shi Jing KANG Lu YAN Department of Mathematics Northwest University Center for Nonlinear Studies Northwest University Xingzhi College Xi'an University of Finance and Economics

The two-component μ-Camassa-Holm equation, the μ-Camassa-Holm equation and the modified μ- Camassa-Holm equation are three nonlocal integrable models. In this paper, it is shown that the two-component μ-Camassa-Holm equation and the μ-Camassa-Holm equation with a linear dispersion admit a kind of nonlocal symmetries, and the modified μ-Camassa-Holm equation does not have such kind of nonlocal symmetry. An number of conservation laws to the modified μ-Camassa-Holm equation and μ-Camassa-Holm equation are obtained.

关键词： Nonlocal symmetry conservation law the two-component μ-Camassa-Holm equation the modi-fied μ-Camassa-Holm equation the μ-Camassa-Holm equation

Gas sensitivity of indium oxide

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中国有色金属学会会刊：英文版 2009年第B09期19卷 80-82页

作者： HUANG shi-zhen LIN Wei CHEN Wen-zhe Fujian Key Laboratory of Microelectronic IC Fuzhou University Fuzhou 350002 China College of Material Science and Engineering Fuzhou University Fuzhou 350002 China

The yellow indium oxide nanoparticles were prepared by sintering the white deposition at 500 ℃. The crystalline indium chloride and ammonia were used as the starting material. The results show that, by analyzing the particles through X-ray diffraction and TEM, the particles are very small, spherical, and the particle size is about 40 nm. The direct-heat components made from indium oxide in Cl2 and NO2 was tested respectively, the component is far more sensitive to NO2 than to Cl2 at low heating temperature, and the status is reversed at high heating temperature..

关键词：氧化铟透射电子显微镜粒子烧结法气敏颗粒大小二氧化氮加热温度白色沉淀

Parametric Research of Experiments on a Carangiform Robotic Fish

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Journal of Bionic Engineering 2008年第2期5卷 95-101页

作者： Qin Yan zhen Han shi-wu Zhang Jie Yang Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China Hefei 230026 P R. China

In this paper, a carangiform robotic fish with 4-DoF （degree of freedom） tail has been developed. The robotic fish has capability of swimming under two modes that are radio control and autonomous swimming. Experiments were conducted to investigate the influences of characteristic parameters including the frequency, the amplitude, the wave length, the phase difference and the coefficient on forward velocity. The experimental results shown that the swimming performance of the robotic fish is affected mostly by the characteristic parameters observed.

关键词： biomimetic robotic fish experimental parameter matrix undulation equation body length velocity

Effects of Dendritic Orientation on Stress Rupture Properties of DD6 Single Crystal Superalloy

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Journal of Iron and Steel Research International 2011年第10期18卷 66-71页

作者： shi zhen-xue LI Jia-rong LIU shi-zhong ZHAOJin-qian National Key Laboratory of Science and Technology on Advanced High Temperature Structural Materials Beijing Institute of Aeronautical Materials Beijing 100095 China

DD6 single crystal superalloy slabs were prepared with seed method in the direetionally solidified furnace with high temperature gradient. The transverse stress rupture properties and fracture hehaviour of the alloy at 760 ℃/758 MPa, 850 ℃/550 MPa and 980 ℃/250 MPa were investigated and compared with those of longitudinal specimens. The transverse stress rupture lives are corresponding with the longitudinal stress rupture lives at 760 ℃/758 MPa and 850 ℃/550 MPa. The transverse stress rupture lives are slightly less than the longitudinal stress rupture lives at 980 ℃/ 250 MPa. The fracture mechanism of the transverse stress rupture of the alloy at 760 ℃/758 MPa shows quasi-cleav- age mode and the fracture mechanism at 980 ℃/250 MPa shows dimple mode, while the fracture mechanism at 850 ℃/ 550 MPa shows quasi-cleavage and dimple mixture mode. At higher temperature and lower stress, the microeracks are easier to initiate and interconnect in the transverse specimen than those in longitudinal specimen because there are interdendritic regions perpendicular to the axis of stress.

关键词： DD6 single crystal superalloy stress rupture property fracture behaviour