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Journal of Materials Science & Technology 2024年第20期187卷 86-100页

作者： Hao Tang Xiaoying Xi Chaofeng Gao Zhongqiang Liu Jiantao Zhang Weiwen Zhang Zhiyu Xiao jeremy heng rao National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510641China Institute of Advanced Additive Manufacturing Ji Hua LaboratoryFoshan 528000China Well Technology Company Limited Foshan 528225China

In this work,a high-strength crack-free TiN/Al-Mn-Mg-Sc-Zr composite was fabricated by laser powder bed fusion(L-PBF).A large amount of uniformly distributed L1_(2)-Al_(3)(Ti,Sc,Zr)nanoparticles were formed during the L-PBF process due to the partial melting and decomposition of TiN nanoparticles under a high *** L1_(2)-Al_(3)(Ti,Sc,Zr)nanoparticles exhibited a highly coherent lattice relationship with the Al *** the prepared TiN/Al-Mn-Mg-Sc-Zr composite samples exhibit ultrafine grain *** addition,the as-built composite containing 1.5 wt%TiN shows an excellent tensile prop-erty with a yield strength of over 580 MPa and an elongation of over 8%,which were much higher than those of wrought 7xxx *** effects of various strengthening mechanisms were quantitatively estimated and the high strength of the alloy was mainly attributed to the refined microstructure,solid solution strengthening,and precipitation strengthening contributed by L1_(2)-Al_(3)(Ti,Sc,Zr)nanoparticles.

关键词： Laser powder bed fusion Aluminum matrix composites Heterogeneous nucleation Strengthening mechanisms Mechanical performance

Effects of direct aging treatment on microstructure,mechanical properties and residual stress of selective laser melted AlSi10Mg alloy

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Journal of Materials Science & Technology 2023年第8期139卷 198-209页

作者： Huaping Tang Chaofeng Gao Yong Zhang Nannan Zhang Chuan Lei Yunjie Bi Ping Tang jeremy heng rao Institute of Advanced Additive Manufacturing Ji Hua LaboratoryFoshan 528200China Department of Materials Science and Engineering Monash UniversityClaytonVIC 3800Australia National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China Hunan Farsoon High-Tech Co. LtdChangsha 410000China

Direct aging treatment is an important post-processing procedure,yet little research has been done on how it balances the mechanical properties and the stress removal for selective laser melted(SLMed)AlSi10Mg ***,we proposed a typical direct aging treatment on SLMed AlSi10Mg alloys,and studied the effects on their microstructure,properties and residual stress *** results indi-cate that the as-built microstructure is mainly composed of fine cellularα-Al and reticulated Si phases,and some pre-existing precipitates and dislocations are found in these *** direct aging treatment promotes the precipitation of nano-scaled Si phases and preserves a network-like Si ***,the strength of the peak-aged alloy increases while the ductility *** the aging temperature in-creases from 160 to 200℃,aging hardening behavior was accelerated *** at 160℃ for 4-9 h removes 32.0%-43.0%of the residual stress,which is attributed to the decomposition of the su-persaturatedα-Al matrix,the precipitation of the nano-Si phase and the exposure of low-angle grain boundaries(LAGBs).Considering the overal alloy performance obtained,over-aging at 160℃ for 4 h is the optimized heat treatment *** this condition,the yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the alloy in the transverse and longitudinal direction are 309.5 MPa,464.4 MPa and 8.3%and 286.4 MPa,464.9 MPa and 5.1%,respectively.

关键词： Selective laser melting AlSi10Mg alloys Direct aging treatment Residual stress removal

Multivariate relationships between microstructure evolution and strengthening mechanisms in laser powder bed fusion of Al-Mn-Sc alloy:towards improved fatigue performance

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Light(Advanced Manufacturing) 2024年第1期5卷 3-18页

作者： Huaping Tang Chaofeng Gao Shiheng Zhang Xiaojing Xiong Sheng Cao Xiaopeng Wu Yunjie Bi jeremy heng rao Institute of Advanced Additive Manufacturing Ji Hua LaboratoryFoshanGuangdong528200China Department of Mechanical Engineering College of EngineeringShantou UniversityShantouGuangdong515063China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

The effects of direct aging treatment(at 300℃ for 5 hours)on selective laser melted(SLMed)Al-4.5Mn-1.5Mg-0.9Sc-0.2Zr alloy were investigated in this work,with the microstructure,fatigue behaviors,and fracture characteristics examined to determine the primary cause of fatigue crack *** results revealed that the microstructure of the investigated alloy comprised fine equiaxed and columnar *** aging treatment,a significant number of nano-scaled Al3(Sc,Zr)precipitates were dispersed within the grains,leading to a substantial increase in *** yield strength improved from 431 MPa to 568 MPa,representing an increase of more than 32%,while the fatigue strength improved from 180 MPa to 220 MPa after aging ***,the fracture toughness decreased significantly from 25.1 MPa·√m to 12.3 MPa·√*** results of the fatigue fracture characteristics indicate that the Mn-rich phase and the formation of defects such as pores and poor powder fusion are the sources of fatigue *** direct aging treatment can significantly increase the yield strength,decrease the rate of fatigue crack propagation,and thus improve the fatigue performance,it deteriorates the fracture toughness,and thus shortens the fatigue life of the alloy as well.

关键词： Selective laser melting Al-Mn-Sc alloys High-cycle fatigue

Experimental Study on Conversion Characteristics of Dual-Mode OWC Models Appropriate for Voyaging

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China Ocean Engineering 2023年第2期37卷 247-257页

作者： WU Bi-jun ZHANG Fu-ming QIN Zi-zhen WU heng-yu rao Xiang Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Key Laboratory of Renewable Energy CASGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China South China Normal University Guangzhou 510631China University of Science and Technology of China Hefei 230026China

Freely movable wave energy converters(WECs) will greatly improve their adaptability to the marine *** this paper, a dual-mode oscillating water column(OWC) WEC with potential sailing capability is proposed. By opening and closing a gate on the side facing the waves, the WEC converts wave energy in the vertical duct(called VD mode) with low sailing resistance or in the backward bend duct(called BBD mode) with high sailing resistance.A small model and a medium model were designed and manufactured. The capture width ratio(CWR) of the small model in the two modes was experimentally studied. The CWR under bidirectional airflow and conversion characteristics under unidirectional airflow of the medium model in the BBD mode were obtained. Tests of the small model show that the peak CWR is 145.2% under regular waves and 90.1% under random waves in BBD mode, and in VD mode the peak CWR is about 60% of that in the BBD mode. Tests of the medium model show that the peak CWR is 228.96% under regular waves, the maximum wave-to-battery efficiency is 63.36% under regular waves and 30.17%under random waves, respectively.

关键词： wave energy oscillating water column(OWC) capture width ratio(CWR) wave-to-battery conversion efficiency

A New Species of Glyphoglossus Günther,1869(Anura:Microhylidae) from Western Yunnan,China

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Asian Herpetological Research 2021年第4期12卷 371-380页

作者： Dongru ZHANG Shuo LIU Lixia ZHANG Hong HUI heng XIAO Dingqi rao State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunming 650223YunanChina Colege of Life Sciences Yunnan UniversityKunming 650091YunanChina Kunming Natural History Museum of Zoology Kunming Institute of ZoologyChinese Academy of SciencesKunming 650223YunanChina Department of Ecology College of Life SciencesHenan Normal UniversityXinxiang 453007HenanChina Research Center for ecological management and protection of the Yellow River Basin Xinxiang 453007HenanChina

A new species of microhylid frog of the genus Glyphoglossus Gunther,1869 is described from Huadianba,Cangshan Mountain,Dali Bai Autonomous Prefecture,Yunnan Province,*** huadianensis,new species,is compared with congeners from China and other parts of Southeast Asia,and was distinguished from the others by the following combination of characters:adult male body size up to 37.8 mm;pupil rounded;supra tympanic fold distinct;tympanum concealed;toe tips obtuse;subarticular tubercles prominent and rounded;foot webbing extensive;outer metatarsal tubercle present;dorsum tuberculate,yellowish-brown/earth-yellow;and a pair of conspicuous large round spots in *** new species is the tenth species of Glyphoglossus to be described,and the second known from China.

关键词： Glyphoglossus huadianensis sp.n. taxonomy morphology China

Dynamic responses of reinforced concrete beams under double-endinitiated close-in explosion

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Defence Technology（防务技术） 2018年第5期14卷 527-539页

作者： Bin rao Li Chen Qin Fang Jian Hong Zhong-xian Liu heng-bo Xiang State Key Laboratory for Disaster Prevention and Mitigation of Explosion and Impact Army Engineering University School of Civil Engineering Southeast University Tianjin Key Laboratory of Civil Structure Protection and Reinforcing Tianjin Chengjian University

The reinforced concrete(RC) structural component might suffer a great damage under close-in *** from distant explosions, blast loads generated by the close-in explosion are non-uniformly distributed on the structural component and may cause both local and structural failure. In this study,an experimental study was conducted to investigate the dynamic responses of RC beams under doubleend-initiated close-in explosions. The experimental results show that the distribution of blast loads generated by the double-end-initiated explosion is much more non-uniform than those generated by single-point detonation, which is caused by the self-Mach-reflection effects. A 3 D finite element model was developed and validated in LS-DYNA by employing the modified K&C model. Intensive numerical calculations were conducted to study the influences of the initiation way, scaled distance and longitudinal reinforcement ratio on the dynamic responses and failure modes of RC beams. Numerical results show that the RC beam suffers greater damage as the cylindrical explosive is detonated at its double ends than the scenario in which the cylindrical explosive is detonated at its central point. RC beams mainly suffer flexural failure and flexure-shear failure under the double-end close-in explosion, and the failure modes of RC beams change from the flexural damage to flexure-shear damage as the scaled distance or the longitudinal reinforcement ratio decreases. The direct shear failure mode is not usually observed in the double-end-initiated explosion, since the intense blast loads is basically concentrated in the midspan of RC beam, which is due to self-Mach-reflection enhancement.

关键词： Reinforced concrete(RC)beam Close-in explosion Failure mode Dynamic response Double-end-initiation

Influence of non-uniform ultrasonic vibration on casting fluidity of liquid aluminum alloy

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China Foundry 2022年第5期19卷 380-386页

作者： Zi-heng Han Zhi-ming Wang Zhi-ping Sun Bing-rong Zhang Wei-feng rao School of Mechanical Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China

The application of ultrasonic vibration to the casting process can be realized through mould(die)***,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling *** influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration *** is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting *** the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting *** decreasing effect is proportional to the vibration gradient.

关键词： ultrasonic vibration vibration gradient aluminum alloy fluidity

Mechanical Property Evaluation of a SLMed Martensitic Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2020年第11期33卷 1466-1476页

作者： Yun Shi Xiaojing Xiong Zhengwu Liu Yi Yang Juan Hou Songquan Wu jeremy H.rao Kai Zhang Aijun Huang Shanghai Aerospace Equipments Manufacturer Co. LtdShanghai 200245China Shanghai Research Center of Complex Metal Parts by Additive Manufacturing Shanghai 200245China Monash(Suzhou)Engineering Technology Co. LtdSuzhou 215123China School of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Future Industries Institute University of South AustraliaMawson LakesSA 5095Australia Monash Centre for Additive Manufacturing(MCAM) Monash UniversityClaytonVIC 3800Australia

A martensitic stainless steel AISI420 fabricated by selective laser melting(SLM)and post-processed by austenitizing and tempering heat treatment was investigated in this *** as-fabricated SLMed AISI420 showed a strong mechanical property anisotropy and low ductility in the longitudinal *** microstructural characterization revealed the presence of austenite and a relatively sharp solidification texture in the as-fabricated state,while the sharp texture was considered as the cause for the mechanical property *** contrast,a fully martensitic microstructure with a very weak texture was achieved after the austenitizing and tempering heat *** mechanical property anisotropy was also fully eliminated,witnessing a significant improvement in the ductility,and thus,comparable mechanical performance with the wrought product was achieved in this study.

关键词： Selective laser melting Microstructures Tensile testing Electron backscattered diff raction(EBSD) Martensitic steel

High uniformity and stability of 1S1R directly stacked for high-density cross-point memory applications

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Rare Metals 2022年第11期41卷 3671-3676页

作者： Zhi-Ying Yu Jia-Yi Zhao Guo-Kun Ma Ao Chen Da-Lei Chen Yi-heng rao Hao Wang Hubei Yangtze Memory Laboratories Wuhan430205China School of Microelectronic Hubei UniversityWuhan430062China School of Physics and Technology Wuhan UniversityWuhan430072China

In this letter,the Ti-doped NbO_(x)-based selector is applied to SiNOx-based resistive random-access memory(RRAM),forming Pt/NbOx(Ti-doped)/SiNO_(x)/Ti one selector-one RRAM device(1S1R),to suppress the sneak path *** fabricated 1S1R exhibits stable direct current(DC)endurance(>200 cycles),suitable memory window(>40),matched selectivity(>40)and high uniformity of switching parameters.

关键词： Ti stability high

CD4^+CXCR5^+ T cells activate CD27^+IgG^+ B cells via IL-21 in patients with hepatitis C virus infection

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Hepatobiliary & Pancreatic Diseases International 2016年第1期15卷 55-64页

作者： Fan-Yun Kong Bo Feng heng-Hui Zhang Hui-Ying rao Jiang-Hua Wang Xu Cong Lai Wei Peking University People’s Hospital Peking University Hepatology InstituteBeijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases

BACKGROUND： Chronic hepatitis C virus （HCV） infection causes the skewing and activation of B cell subsets, but the characteristics of IgG＋ B cells in patients with chronic hepa- titis C （CHC） infection have not been thoroughly elucidated. CD4＋CXCR5＋ follicular helper T （Tfh） cells, via interleukin （IL）-21 secretion, activate B cells. However, the role of CD4＋CXCR5＋ T cells in the activation ofIgG＋ B cells in CHC patients is not clear. METHODS： The frequency of IgG＋ B cells, including CD27-IgG＋ B and CD27＋IgG＋ B cells, the expression of the activation markers （CD86 and CD95） in IgG＋ B cells, and the percentage of circu- lating CD4＋CXCR5＋ T cells were detected by flow cytometry in CHC patients （n=70） and healthy controls （n=25）. The con- centrations of serum IL-21 were analyzed using ELISA. The role of CD4＋CXCR5＋ T cells in the activation of IgG＋ B cells was investigated using a co-culture system. RESULTS： A significantly lower proportion of CD27＋IgG＋ B cells with increased expression of CD86 and CD95 was observed in CHC patients. The expression of CD95 was negatively correlated with the percentage of CD27＋IgG＋ B cells, and it contributed to CD27＋IgG＋ B cell apoptosis. Circulating CD4＋CXCR5＋ T cells and serum IL-21 were significantly increased in CHC patients. Moreover, circulating CD4＋CXCR5＋ T cells from CHC patients induced higher expressions of CD86 and CD95 in CD27＋IgG＋ B cells in a co-culture system; the blockade of the IL-21 decreased the expression levels of CD86 and CD95 in CD27＋IgG＋ B ***： HCV infection increased the frequency of CD4＋CXCR5＋ T cells and decreased the frequency of CD27＋IgG＋ B cells. CD4＋CXCR5＋ T cells activated CD27＋IgG＋ B cells via the secretion of IL-21.

关键词： chronic hepatitis C IgG+ B cells CD4+CXCR5+ T cells