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Pronounced impact of size and shape effects on creep rupture life of a K439B superalloy combustion chamber casting simulator

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China Foundry 2025年

作者： Wen-tong Liu Yi-dong Wu Lei Gao Jing-yang Chen Cheng-bo Xiao Xi-dong Hui State Key Laboratory for Advanced metals and Materials University of Science and Technology Beijing Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The size and shape effect(SSE) of components has become a critical issue for mechanical properties, application reliability, and processing. In this study, the creep rupture life(CRL) of components with different wall thicknesses and positions in a combustion chamber casing simulator made of K439B superalloy was investigated. The intrinsic mechanisms of the SSE were explored from the dendrite structure, volume fraction and size of the γ' phase, and element segregation, etc. It is shown that this casting exhibits a strong SSE of creep rupture life, characterized by a significant difference in the CRL values up to 60% with the variation of wall thickness and position in the casing. In terms of casting technology, the influence of SSE on CRL is actually determined by the cooling rate. The SSE on the creep rupture life originates from the dendrite structure(such as the secondary dendrite arm spacing), volume fraction size of the γ' phase in the dendrite trunk, and elements segregation rate. This work may have implications for the design and application of engineering components with large sizes and complex structures.

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Dynamic performance enhancement in Ti/Au ohmic contacts on β-Ga2O3-on-Si C substrates: evidence from pulsed measurements

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Science China(Information Sciences) 2025年第1期68卷 400-401页

作者： Chenyu LIU Yibo WANG Wenhui XU Shuqi HUANG Chunxiao YU Zeyu YANG Xiaole JIA Xiaoxi LI Bochang LI Zhengdong LUO Cizhe FANG Yan LIU Tiangui YOU Xin OU Genquan HAN School of Microelectronics Xidian University Suzhou institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Shanghai institute of Microsystem and Information Technology Chinese Academy of Sciences Hangzhou institute of Technology Xidian University

Titanium/Gold （Ti/Au） metals have been widely employed as ohmic metal contacts on n+Ga2O3,exhibiting the specific contact resistance （ρc） of 10-5-10-6Ω·cm2[1].But previous studies have revealed the presence of a defective Ga2O3layer and reactive Ti-Ga2O3layer at the annealed Ti/*** an interfacial layer can afect the performance of ohmic contact,which may become more pronounced in power devices subjected to electrical stress and high-frequency ***,there have been no reports on the impact of bias stress effects and dynamic degradation of Ti/Au ohmic contacts on n+Ga2O3.

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Electrical conductivity of Cu-Ag in situ filamentary composites

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中国有色金属学会会刊：英文版 2007年第2期17卷 378-383页

作者：宁远涛张晓辉吴跃军 Kunming institute of Precious metals

The electrical conductivity of Cu-10Ag in situ filamentary composite was studied during the deformation and annealing processes. The dependence of electrical resistivity of the deformed composites on the true strain presents a two-stage change with increase of the true strain. The intermediate heat treatment and the stabilized annealing treatment to the deformed composite promote the separation of Ag precipitate, and increase the electrical conductivity. The maximum conductivity of the composite experienced the stabilizing heat treatment can reach about 97% IACS with σb≥400 MPa at 550 ℃ annealing, and reach about 70% IACS with σb≥1 250 MPa at 300 ℃ annealing. The corresponded strength of the composite was reported. The microstructure reason for the changes of the conductivity was discussed.

关键词： Cu-Ag合金丝状复合材料导电性显微结构

Orbitronics for energy-efficient magnetization switching

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Science China(Information Sciences) 2025年第1期68卷 398-399页

作者： Yuxuan YAO Daoqian ZHU Qingtao XIA Jianing LIANG Yuhao JIANG Zhiyang PENG Jiaxu LI Chen XIAO Renyou XU Wenwen WANG Xiantao SHANG Shiyang LU Dapeng ZHU Hong-Xi LIU Kaihua CAO Weisheng ZHAO Fert Beijing institute School of Integrated Circuit Science and Engineering Beihang University National Key Lab of Spintronics Institute of International Innovation Beihang University Qingdao Research institute Beihang University Truth Memory Corporation

Spin-orbit torque （SOT）,as a promising writing method for magnetic random-access memory （MRAM）,has garnered widespread interest for over a decade [1].Heavy metals,such as β-W,have been broadly adopted as spin current sources,but suffer from phase change at a limited thickness,resulting in a dramatic reduction of the charge-tospin conversion efficiency θSH[2].The thickness limitation leads to stringent etching conditions and large distribution among devices,posing challenges for simultaneously satisfying SOT efficiency,etching-stop margins,and back-end-ofline （BEOL） compatibility.

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Partial phase diagram of Au-Ag-Dy ternary system

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中国有色金属学会会刊：英文版 2005年第4期15卷 738-742页

作者：张康侯陈江 Kunming institute of Precious metals

On the basis of Au-Ag, Au-Dy and Ag-Dy binary phase diagrams, the 700℃ isothermal section of Au-Ag-Dy ternary system（Dy≤35%, mole fraction） was established by X-ray diffraction analysis, differential thermal analysis and optical microscopy. It is found that there is a long single-phase region, Au（Ag） or Ag（Au）, along the Au-Ag binary isomorphous system on the gold-silver-rich side of the 700℃ isothermal section and between the binary compound Au2Dy and Ag2Dy there is the all proportional solid solution, （Au2Dy） or （Ag2Dy）. It is confirmed that the partial 700℃ isothermal section consists of six single-phase regions: solid solution Au（Ag） or Ag（Au）, （Au2Dy） or （Ag2Dy）, Au6Dy, Au51Dy14, Au3Dy and Ag51Dy14; nine binary-phase regions: （Au2Dy）+Au（Ag）, Au6Dy+Au（Ag）, Au（Ag）+Ag51Dy14, Ag51Dy14+（Au2Dy）, Au3Dy+（Au2Dy）, Au3Dy+Au51Dy14, Au51Dy14+Au6Dy, Au51Dy14+Au（Ag） and Au（Ag）+Au3Dy;four ternary regions: Ag51Dy14+（Au2Dy）+Au（Ag）, （Au2Dy）+Au（Ag）+Au3Dy, Au（Ag）+Au3Dy+Au51Dy14 and Au51Dy14+Au（Ag）+Au6Dy. No new ternary compound is formed in the gold-silver-rich field（Dy≤35%） of the Au-Ag-Dy ternary system.

关键词：金银镝三重系统等温线相平衡热力学合金相图

Effect of thermal shield and gas flow on thermal elastic stresses in 300mm silicon crystal

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Rare metals 2006年第Z2期25卷 45-50页

作者： GAO Yu XIAO Qinghua ZHOU Qigang DAI Xiaolin TU Hailing General Research institute for Nonferrous metals Beijing 100088 China General Research Institute for Nonferrous Metals Beijing 100088 China General Research Institute for Nonferrous Metals Beijing 100088 China General Research Institute for Nonferrous Metals Beijing 100088 China General Research Institute for Nonferrous Metals Beijing 100088 China

The thermal elastic stresses induced in 300 mm Si crystal may be great troubles because it can incur the generation of dislocations and undesirable excessive residual stresses. A special thermal modeling tool, CrysVUn, was used for numerical analysis of thermal elastic stresses and stress distribution of 300 mm Si crystal under the consideration of different thermal shields and gas flow conditions. The adopted governing partial equations for stress calculation are Cauchy′s first and second laws of motion. It is demonstrated that the presence and shape of thermal shield, the gas pressure and velocity can strongly affect von Mises stress distribution in Si crystal. With steep-wall shield, however, the maximal stress and ratio of high stress area are relatively low. With slope-wall shield or without shield, both maximal stress and ratio of high stress area are increased in evidence. Whether thermal shields are used or not, the increase of gas flow velocity could raise the stress level. In contrast, the increase of gas pressure cannot result in so significant effect. The influence of thermal shield and gas flow should be attributed to the modification of heat conduction and heat radiation by them.

关键词： thermal elastic stress simulation 300 mm Si single crystal

New method of direct chill casting of Al-6Si-3Cu-Mg semisolid billet by annulus electromagnetic stirring

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1591-1596页

作者：汤孟欧徐骏张志峰白月龙 General Research institute for Nonferrous metals

The electromagnetic direct chill （EMDC） casting process is a welt-established production route for aluminum alloy ingot, however, the skin effect restricts the casting diameter. In order to avoid this problem, annulus electromagnetic direct chill （A-EMDC） casting process has been developed. A three-dimension finite element computational model of A-EMDC casting process was established by using ANSYS Magnetic-Nodal programs and FLOTRAN CFD programs. Microstruetures of A-EMDC casting semi-solid Al-6Si-3Cu-Mg alloy billets were investigated. Two pairs of vortexes occur within the crystallizer with opposite direction in A-EMDC. The annulus gap is advantageous to increasing circulate flow, reducing the temperature gradient as well as shallowing liquid sump depth. The microstructure obtained by A-EMDC is globular or rosette-like, and the microstructure is homogeneous in the billet.

关键词： electromagnetic stirring semi-solid continuous casting Al-6Si-3Cu-Mg alloy

Microstructure and tensile properties of Ti-62421S alloy plate with different annealing treatments

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Rare metals 2018年第7期37卷 568-573页

作者： Yong-Ling Wang Xiao-Yun Song Wen Ma Wen-Jing Zhang Wen-Jun Ye Song-Xiao Hui State Key Laboratory of Nonferrous metals and Processes General Research Institute for Nonferrous Metals Division of Science and Technology Information General Research Institute for Nonferrous Metals

Ti-62421S （Ti-6A1-2Sn-4Zr-2Nb-lMo-0.2Si） is a novel short-time using high-temperature titanium alloy. The effects of annealing on microstructure and tensile properties of Ti-62421S alloy plate were studied through optical microscopy （OM）, electron probe microanalysis （EPMA）, transmission electron microscopy （TEM）, and tensile tests. The results show that, with annealing tem- perature increasing, the volume fraction of primary α（αp）- phase decreases while that of transformed β（βt）-structure and secondary α （αs）-phase increases. The room-temperature strength and plasticity are insensitive to annealing temperature. However, with annealing temperature increasing, the tensile strength decreases at 550℃, while increases at 600 and 650℃ instead. It is suggested that, at 550℃, the strengthening mechanism is mainly boundary strengthening and the biggest contributor is ap-phase by providing αp/β-boundary area. Above 600 ℃, the strengthening mechanism is grain strengthening, where αs-phase strengthens the β-phase.

关键词： High temperature titanium alloy Ti-62421S Heat treatment Microstructure Tensile properties

Sleep as a window to understand and regulate Alzheimer's disease:emerging roles of thalamic reticular nucleus

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Neural Regeneration Research 2025年第6期20卷 1711-1712页

作者： Haoqi Sun Shiqian Shen Robert J.Thomas M.Brandon Westover Can Zhang Department of Neurology Beth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Center for Translational Pain Research Department of AnesthesiaCritical Care and Pain MedicineMassachusetis General HospitalHarvard Medical SchoolBostonMAUSA Division of Pulmonary Critical Care and Sleep MedicineDepartment of MedicineBeth Israel Deaconess Medical CenterHarvard Medical SchoolBostonMAUSA Genetics and Aging Research Unit McCance Center for Brain HealthMass General Institute for Neurodegenerative DiseaseDepartment of NeurologyMassachusetts General HospitalHarvard Medical SchoolBostonMAUSA

Introduction:Alzheimer 's disease(AD) is a common neurodegenerative disorder and the primary cause of dementia. Considerable evidence supports the “amyloid hypothesis,” stating that the pathogenesis of AD is primarily caused by the deposition of amyloid-β(Aβ), which drives tau phosphorylation, neuroinflammation, and neurodegeneration in the brain. The amyloid hypothesis is strengthened by the significant and moderate benefit of lecanemab, a humanized antibody through an anti-amyloid mechanism,showing slowed clinical decline(van Dyck et al.,2023). The recent positive results of anti-amyloid trials have brought back focus on the amyloid hypothesis through biochemical, genetic, and pharmacological approaches(Zhang, 2023).

关键词： Alzheimer inflammation hypothesis