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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

Effects of Ru on the microstructure and phase stability of a single crystal superalloy

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International Journal of Minerals,Metallurgy and Materials 2012年第11期19卷 1004-1009页

作者： Zhen-xue shi Jia-rong Li shi-zhong liu Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical MaterialsBeijing 100095China

Two experimental single crystal superalloys, the Ru-free alloy and the Ru-containing alloy with [001 ] orientation, were cast in a directionally solidified furnace, while other alloying element contents were kept unchanged. The effects of Ru on the microstructure and phase stability of the single crystal superalloy were investigated, y＇ directional coarsening and rafting were observed in the Ru-free alloy and Ru-containing alloy after long-term aging at 1070~C for 800 h. Needle-shaped o topologically close packed （TCP） phases precipitated and grew along the fixed direction in both the alloys. The precipitating rate and volume fraction of TCP phases decreased significantly by adding Ru. The compositions ofy and y＇ phases measured using an energy-dispersive X-ray spectroscope （EDS） in transmission electron microscopy （TEM） analysis showed that the addition of Ru lessened the partition ratio of TCP forming elements, Re, W and Mo, and decreased the satu- ration degrees of these elements in y phase, which can enable the Ru-containing alloy to be more resistant to the formation of TCP phases. It is indicated that the addition of Ru to the Ni-based single crystal superalloy with high content of the refractory alloying element can enhance phase stability.

关键词： superalloys nickel alloys single crystals ruthenium microstructure phase stability

Tensile Behavior of the Second Generation Single Crystal Superalloy DD6

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Journal of Iron and Steel Research International 2015年第8期22卷 738-742页

作者： Zhen-xue shi shi-zhong liu Jian YU Jia-rong LI Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

Tensile properties of the second generation single crystal superalloy DD6 were investigated from 20 ℃ to 1 100 ℃. Microstructure evolution and fracture mechanism were examined by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results show that the tensile strength decreases slightly with increasing temperature from 20 ℃ to 400 ℃. The tensile strength of the alloy increases with the increase of temperature from 400 ℃ to 800 ℃. Above 800 ℃, the yield strength of the alloy decreases greatly with increasing temperature. The elongation and contraction of area almost present opposite tendency in contrast to changes of the tensile strength. At lower and intermediate temperature （from 20 ℃ to 850 ℃）, the tensile fracture mechanism shows quasi-cleavage mode, while at high temperature （980 ℃ and 1 100 ℃）, it is dimple mode. The γ＇ precipitate morphology still maintains cubic after tensile fracture at lower and intermediate temperature. The γ＇ phase changes into rectangular solid at high temperature. The γ＇ phase is sheared by anti-phase boundary （APB） or stacking faults at lower and intermediate temperature. At high temperature, dislocations overcome γ＇ through by-passing mechanism.

关键词： single crystal superalloy DD6 tensile behavior microstructure evolution

Effect of cellular recrystallization on tensile properties of a nickel-based single crystal superalloy containing Re and Ru

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Journal of Iron and Steel Research International 2017年第10期24卷 1059-1064页

作者： Zhen-xue shi shi-zhong liu Xiao-dai Yue Li-jie Hu Wan-peng Yang Xiao-guang Wang Jia-rong Li Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical MaterialsBeijing 100095China

A nickel-based single crystal superalloy containing Re and Ru was cast in a directional solidification *** single crystal specimens after standard heat treatment were grit blasted with different pressures and then heat treated at 1100°C for 4 hunder vacuum *** evolution of recrystallized microstructure and its effect on the tensile properties at 850 and 980°C were *** heat treatment,the cellular microstructure was observed,and the thickness of the cellular recrystallization zone increases with the increase in grit blasting *** appearance of the cellular structure undermines the tensile *** the tensile strength and elongation decrease with increasing the thickness of the cellular *** recrystallized grain boundaries can act as the channels for the crack initiation and propagation during tensile *** low bearing capacity of recrystallized layers and the local stress concentration resulting from the notch effect of cracking were the main reasons for the decrease of tensile properties.

关键词： Single crystal superalloy Cellular recrystallization Tensile property Microstructure Fracture morphology

Dependence of Soil Respiration on Soil Temperature and Soil Moisture in Successional Forests in Southern China

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Journal of Integrative Plant Biology 2006年第6期48卷 654-663页

作者： Xu-Li Tang Guo-Yi Zhou Shu-Guang liu De-Qiang Zhang shi-zhong liu Jiong Li Cun-Yu Zhou South China Botanical Garden the Chinese Academy of Sciences Guangzhou 510650 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China Science Applications International Corporation （ SAIC） US Geological Survey （ USGS） National Center for Earth Resources Observation and Science （EROS） Sioux Falls South Dakota 57198 USA

The spatial and temporal variations in soil respiration and its relationship with biophysical factors In forests near the Tropic of Cancer remain highly uncertain. To contribute towards an Improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured In three successional subtropical forests at the Dlnghuahan Nature Reserve （DNR） In southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and Its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared In successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season （April-September） and with low rates In the cool dry season （October-March）. Soil respiration measured at these forests showed a clear Increasing trend with the progressive succession. Annual mean （± SD） soil respiration rate In the DNR forests was （9.0 ± 4.6） Mg CO2-C/hm^2 per year, ranging from （6.1 ± 3.2） Mg CO2-C/hm^2 per year in early successional forests to （10.7 ± 4.9） Mg CO2-C/hm^2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation In DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture Increased with progressive succession processes. This increase is caused, in part, by abundant respirators In advanced-successional forest, where more soil moisture is needed to maintain their activities.

关键词： Dinghushan Nature Reserve moisture sensitivity Q10 soil CO2 efflux soil respiration subtropical forests successional forests temperature sensitivity Tropic of Cancer.

Pollen Grain Germination and Pollen Tube Growth in Pistil of Rice

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Rice science 2008年第2期15卷 125-130页

作者： CHEN shi-qiang WANG zhong liu Man-xi XIE Zhao-wei WANG Hui-hui Laboratory of Crop Inheritance Cultivation ＆ Physiology Yangzhou University Yangzhou 225009 China

The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope. The stigma was removed at different time points after pollination to study its effect on seed setting rate. The rice pollen grain started to germinate at 2 min after pollination and the pollen tube penetrated stigma into style in 5-10 min, 30 min later the end of pollen tube reached the bottom of ovary, and only some pollen tubes arrived at embryo sac at 40 min after pollination. Meanwhile, a small amount of callose began to deposit in the pollen tubes, a great deal of callose was observed at 50 min after pollination, whereas the pollen grain began to shrink. The growing rates of pollen tube in the rice stigma, style and ovary were 1500, 5000, and 5400 μm/h, respectively. The seed setting rate was quite low when the stigma was removed at about 10-15 min after pollination, gradually increased when it removed at 20 min to 50 min after pollination, and over 60% when it removed at 50 min after pollination and finally tended to be stable.

关键词： rice pollen grain germination pollen tube growth seed setting rate microscopic observation

Cobalamin-dependent radical S-adenosyl-L-methionine protein functions with a partner to successively methylate tricyclic indole alkaloid for chuangxinmycin maturation and derivatization

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Science China Chemistry 2025年第1期68卷 308-316页

作者： Sili Wang Jiancheng Huang Yanan Du Wei Huang Yufeng Xue Xiaokun Xu Guannan zhong Yuanyuan shi Bin Hong Xiaoying Bian Wen liu State Key Laboratory of Chemical Biology Shanghai Institute of Organic Chemistry University of Chinese Academy of SciencesChinese Academy of Sciences State Key Laboratory of Microbial Technology Shandong University National Health Commission (NHC) Key Laboratory of Biotechnology for Microbial Drugs Institute of Medicinal BiotechnologyChinese Academy of Medical Science & Peking Union Medical College

Cobalamin(Cbl)-dependent radical S-adenosyl-L-methionine(SAM) proteins constitute the largest collection of the radical SAM superfamily that has hundreds of thousands of individual members. Many of these proteins are involved in the biosynthesis of pharmaceutically important natural products to catalyze chemically demanding reactions. In the biosynthetic pathway of chuangxinmycin(CXM), a unique indole alkaloid antibiotic with potent anti-infective activity, functionalization of the characteristic thiopyrano[4,3,2-cd]indole scaffold by regio-and stereoselective C3-methylation is believed to rely on a Cbl-dependent radical process, which, however, remained to be reconstituted biochemically. We here report the dissection of this enzymatic process, which requires the incorporation of Cxm8, a Cbl-dependent radical SAM protein, with Cxm9, a DUF5825family protein that shares no homology to any proteins of known functions. Cxm8 and Cxm9 function together by forming an unexpected heterodimeric complex that selectively catalyzes C3-methylation of the tricyclic indole-S-hetero ring system in a successive manner, achieving CXM and a recently identified, C3-dimethylated congener. Detailed biochemical characterization,isotope labeling, structural simulation and bioinformatics analysis rationalized the catalysis of the Cxm8/Cxm9 complex and particularly the necessity of the DUF5825 protein for C3-methylase activity. This is the first example that a Cbl-dependent protein acts with a partner to exhibit radical SAM activity.

关键词： cbl-dependent radical SAM protein biosynthesis chuangxinmycin stereoselective methylation

Orientation dependence of transverse tensile properties of nickel-based third generation single crystal superalloy DD9 from 760 to 1100 ℃

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Transactions of Nonferrous Metals Society of China 2019年第3期29卷 558-568页

作者： Wan-peng YANG Jia-rong LI shi-zhong liu Zhen-xue shi Jin-qian ZHAO Xiao-guang WANG Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials Beijing 100095 China

At temperatures ranging from 760 to 1100 °C, the tensile properties of a nickel-based third generation single crystal superalloy DD9 with [100],[120] and [110] orientations were studied. The microstructures and fracture surfaces were observed by OM, SEM and TEM. Results show that the tensile strength of [100] specimen is higher than that of [120] and [110] specimens at 760 and 850 °C;while at the temperatures higher than 980 °C, the tensile strength of all specimens has little difference. The fracture mechanisms of [100],[120] and [110] specimens are the same at 760 and 980 °C. At 1100 °C, the fracture surfaces of [100] and [120] specimens are characterized by dimple features;while [110] specimen shows mixed quasi-cleavage and dimple featured fracture surfaces. At 760 °C, obvious superlattice stacking faults (SSFs) are observed only in [100] specimen;while at 1100 °C, the dislocation configurations of all specimens are similar. The difference in the number of potential active slip systems in [100],[120] and [110] specimens during the tensile deformation process is the main reason for the transverse tensile anisotropy.

关键词： third generation single crystal superalloy DD9 transverse tensile properties anisotropy fracture surface

Single-cell technologies: current and near future

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Science China Life Sciences 2025年第1期68卷 1-4页

作者： Chenfei Wang Qi liu Xiaohui Fan Tieliu shi Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration Ministry of EducationOrthopedics DepartmentTongji HospitalBioinformatics DepartmentSchool of Life Sciences and TechnologyTongji University Frontier Science Center for Stem Cells School of Life Sciences and TechnologyTongji University Translational Medical Center for Stem Cell Therapy and Institute for Regenerative Medicine Shanghai East HospitalBioinformatics DepartmentSchool of Life Sciences and TechnologyTongji University Research Institute of Intelligent Computing Zhejiang Lab Pharmaceutical Informatics Institute College of Pharmaceutical SciencesZhejiang University National Key Laboratory of Chinese Medicine Modernization Innovation Center of Yangtze River DeltaZhejiang University Center for Bioinformatics and Computational Biology Shanghai Key Laboratory of Regulatory Biologythe Institute of Biomedical Sciences and School of Life SciencesEast China Normal University Key Laboratory of Advanced Theory and Application in Statistics and Data Science (MOE) School of StatisticsEast China Normal University

Single-cell technologies enable the indepth exploration of multiple biological hierarchies at the scale of individual cells,which have deepened our knowledge of cellular diversity, tissue organization, and overall organism function(Sun et al.,2024). In 2009, single-cell RNA sequencing(sc RNA-seq) was first developed as a powerful tool to dissect gene expression and uncover transcriptional *** the rapid advancement of technology, single-cell approaches have expanded to encompass other omics, such as genomics, epigenomics, proteomics,and metabolomics.

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