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Effects of hot deformation and in-situ ZrB2 particle on microstructure and tensile performance of AA7085 composite sheets

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Journal of Iron and Steel Research International 2024年第7期31卷 1778-1791页

作者： Jiang-jing Wu Xi-zhou Kai Chuang Guan yu-tao zhao School of Material Science and Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

To provide a new idea to reduce anisotropy for sheets in the thickness direction by microstructure modification and,mean-while,maintain or even enhance tensile performance,the in-situ ZrB2 particle/AA7085 composite sheets with thicknesses of 1,2,3,and 6 mm were *** as-cast grain size was significantly refined by the heterogeneous nucleus of the ZrB2 *** microstructure results show that severe hot deformation converts as-cast disordered microstructure into a sequential microstructure by crushing the remanent phases and matrix into a fiber *** the solid solution and aging heat treatment,the composite sheets exhibit largely recrystallized grains compared with partially recrystallized grains in the matrix sheets,and weak or even free texture exists in the *** grain size in the composite sheets decreases with the increase in thickness *** the thickness range of 1-3 mm,the composite sheets maintain a similar tensile per-formance as that in matrix sheets,while the strength and ductility in the 6-mm-thick composite sheet are improved.

关键词： Composite sheet Grain structure Texture Dislocation Strengthening

Microstructure and properties of Al_3Zr/2024Al in situ composites after forging

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Rare Metals 2016年第12期35卷 920-925页

作者： Lei Jiao yu-tao zhao Jian-Chao Chen Long Chen School of Materials Science and Engineering JiangsuUniversity

To research the influencing rule of severe plastic deformation on Al matrix in situ composites, 10wt%Al3Zr/2024Al in situ particle-reinforced composite was prepared by direct melt reaction （DMR）, and then, the composite was hot-forged by one direction with 90% plastic deformation. Then, the microstructure of the forging state composite was observed, and the change law of mechanical properties and friction performances after and before plastic deforming was compared. The results indicate that the Al3Zr-reinforced particle rotates and breaks into smaller size of 10-20μm with the matrix flow; in addition, these smaller particles distribute more orderly in orientation and dispersedly. The 2024 matrix grain changes from as-cast tissue to fibrous tissue with length of 100 μm along the forging direction. Some mechanical properties of composites hot-forged by one direction with 90 % plastic deformation are improved much obviously. For example, the tensile strength is improved by 39.75 %, reaching 225 MPa, and the hardness is improved by 35.84 %, reaching HBW 76.83. Besides, the wear rate reduces, wear depth and area decline, and the wear-resisting property is improved after hot forging.

关键词： Al3Zr/2024Al in situ composites Forging Microstructure Mechanical properties Wear-resisting property

Comparative experiment on layered Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O_2 as the alternative material for LiCoO_2

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Journal of University of Science and Technology Beijing 2007年第2期14卷 173-177页

作者： Jingjing Liu Weihua Qiu Lingyan yu Hailei zhao tao Li Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

This work was financially supported by the National Natural Science Foundation of China （No.50472093）.

关键词： Li(Ni1/3Co1/3Mn1/3)O2 cathode material lithium-ion batteries LiCoO2

Preparation and tensile properties of DD5 single crystal castings

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International Journal of Minerals,Metallurgy and Materials 2016年第6期23卷 683-690页

作者： Xiang-feng Liang yu-tao zhao Zhi-hong Jia Chi Zhang School of Material Science and Engineering Jiangsu University

The preparation procedure of DD5 single crystal castings was optimized. The microstructure characteristics of DD5 single crystal superalloy were investigated by microstructure observation and segregation behavior examination. The results show that the grain orientation is optimized by constraining the spiral crystallizer in [001] orientation and spatial scale. Also, the γ＇ phase of inter-dendrites is larger and more irregular than that in dendrite arms. High temperature tensile tests of DD5 single crystal castings exhibit that the peak stress increases with increasing temperature, while the area reduction shows an opposite trend, when the temperature is below 800℃; meanwhile, when the temperature is between 800℃ and 1000℃, the fracture stress of the alloy is the same as the peak stress. The fracture mode changes from shear to ductile with increasing temperature from 600℃ and 1000℃.

关键词： superalloys single crystals segregation tensile properties alloy preparation castings

Microstructure and mechanical properties of AZ91 magnesium alloy subject to deep cryogenic treatments

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International Journal of Minerals,Metallurgy and Materials 2013年第9期20卷 896-901页

作者： Gui-rong Li Hong-ming Wang yun Cai yu-tao zhao Jun-jie Wang Simon P.A. Gill School of Materials Science & Engineering Jiangsu University The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of Sciences Department of Engineering University of Leicester

AZ91 magnesium alloy was subjected to a deep cryogenic treatment. X-ray diffraction （XRD）, scanning electronic microscopy （SEM）, and transmission electronic microscopy （TEM） methods were utilized to characterize the composition and microstructure of the treated samples. The results show that after two cryogenic treatments, the quantity of the precipitate hardening β phase increases, and the sizes of the precipitates are refined from 8-10μm to 2-4μm. This is expected to be due to the decreased solubility of aluminum in the matrix at low temperature and the significant plastic deformation owing to internal differences in thermal contraction between phases and grains. The polycrystalline matrix is also noticeably refined, with the sizes of the subsequent nanocrystalline grains in the range of 50-100 nm. High density dislocations are observed to pile up at the grain boundaries, inducing the dynamic recrystallization of the microstructure, leading to the generation of a nanocrystalline grain structure. After two deep cryogenic treatments, the tensile strength and elongation are found to be substantially increased, rising from 243 MPa and 4.4% of as-cast state to 299 MPa and 5.1%.

关键词： magnesium alloys cryogenic treatment microstructure mechanical properties

Influence of heat treatments on incipient melting structures of DD5 nickel-based single crystal superalloy

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China Foundry 2023年第5期20卷 395-402页

作者： Zhi-hong Jia Chen-yang Li Wen-xiang Jing Xiang-feng Liang Ze-kun Zhang Jia-le Xiao yu-tao zhao School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

The evolution of microstructure and formation mechanism of incipient melting microstructure of DD5 single crystal superalloy during solution heat treatment were studied by scanning electron microscopy(SEM),electron probe microanalysis(EPMA),and energy dispersive spectroscopy(EDS).The solidus and liquidus of single crystal alloy were obtained by differential scanning calorimetry(DSC).Results show that the mosaic-like eutectic and fan-like eutectic are dissolved at first,and the coarseγ'phase is dissolved later during the solution heat treatment of 1,390°C/2 h+1,310°C/4 h+1,320°C/10 h+air cooling(AC).The composition segregations of Al,Ta,W and Re are 0.99,0.96,1.04 and 1.16,respectively,which close to *** incipient melting is caused by the low local temperature of the alloy,and the micropore region with a lower melting point is the preferred position for incipient melting.

关键词： superalloy solution heat treatment eutectic composition segregation incipient melting

Copper-Catalyzed Ring-Opening/Borylation of Cyclopropenes

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CCS Chemistry 2022年第4期4卷 1232-1237页

作者： Ming-Yao Huang yu-tao zhao Hao Chai Cheng-Da Zhang Shou-Fei Zhu The State Key Laboratory and Institute of Elemento-Organic Chemistry College of ChemistryNankai UniversityTianjin 300071

Since organoboron compounds readily undergo a diverse array of transformations and are widely used in various fields,the development of C-B-bondforming reactions have attracted considerable ***,we report a new method for forming C-B bonds by means of Cu-catalyzed ring-opening/borylation reactions of *** method provides efficient access to a new type of stable allylborane-Lewis base adduct,which is a versatile *** configuration of the products can be well controlled with this method,and some of the configurations we obtained are inaccessible by other catalytic methods for generating *** studies indicated that the reactions proceed via insertion of an alkenyl Cu carbene—generated in situ by cyclopropene ring opening—into the B-H bond;the ring-opening step determines both the rate and stereochemistry.

关键词： cyclopropenes carbenes B-H bond insertion copper catalysis allylboranes

Gradient maturation experiment on hairs implies taphonomic changes in fossil hairs

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Science China Earth Sciences 2025年第1期68卷 62-73页

作者： Xin LI Yibo ZHOU tao zhao Xingjian HE Yanhong PAN State Key Laboratory for Mineral Deposits Research Center for Critical Earth Material Cycling Centre for Research and Education on Biological Evolution and Environment and Frontiers Science School of Earth Sciences and Engineering Nanjing University Institute of Palaeontology Yunnan Key Laboratory of Earth System Science Yunnan Key Laboratory for PalaeobiologyYunnan University

Mammalian hair, as a key feature related to endothermy, physical protection, and camouflage, has a long geohistorical record that dates back even to the Mesozoic. However, the limited information on the taphonomy of hair hinders the understanding of its evolutionary significance in deep time. To address this, we conducted taphonomic experiments to simulate the transformation process of black hair. The changes in the morphological structure, microscopic characteristics, and chemical composition of hair during the simulated fossilization process were documented by scanning electron microscopy, Fourier transform infrared(FTIR) spectroscopy, and Raman spectroscopy. Our results revealed that damage to the morphology of hair began at a mild temperature(150–175°C), and hair transformed into a fluid-like mass at a relatively high temperature(200°C). In addition, the morphological structure of melanosomes had relatively greater preservation potential than keratins did, and the microscopic features of melanosomes were persistently stable. The Raman and FTIR spectra indicated that the characteristic melanin and keratin peaks changed as the temperature increased. Although the chemical signals were not lost completely, the variations in the characteristic amide bands in the FTIR spectra indicate that the keratins severely degraded at high temperatures(>200°C), whereas the characteristic melanin bands in the Raman spectra suggested that melanin signals were still recognizable, even at high temperatures(>200°C). These results were confirmed by principal component analysis(PCA) and principal component analysis linear discriminant analysis(PCA–LDA). In addition, the Raman signals of all the samples in the simulated experiments were distinguished from the signals of common geological carbonaceous materials(humic acid), which suggested that Raman spectroscopy can be used to detect melanin in fossils.

关键词： Mammalian hair Melanin Keratin Fossilization Experimental taphonomy

Preparation of FeCoNi medium entropy alloy from Fe^(3+)-Co^(2+)-Ni^(2+)solution system

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 92-101页

作者： Zongyou Cheng Qing zhao Mengjie tao Jijun Du Xingxi Huang Chengjun Liu Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China Engineering Research Center of Frontier Technologies for Low-carbon Steelmaking(Ministry of Education) Shenyang 110819China

In recent years,medium entropy alloys have become a research hotspot due to their excellent physical and chemical *** controlling reasonable elemental composition and processing parameters,the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower *** this paper,a FeCoNi medium entropy alloy precursor was prepared via sol-gel and coprecipitation methods,respectively,and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen *** phases and magnetic properties of FeCoNi medium entropy alloy were *** showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500℃.Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal *** alloy prepared by hydrogen reduction was uniform and showed a relatively high ***,the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.

关键词： medium entropy alloy sol-gel co-precipitation carbothermal hydrogen reduction