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IEEE Electron Device Letters 2025年第5期46卷 817-820页

作者： Kim, Seokjun Kim, Eungkyun Walwil, Husam Shoemaker, Daniel C. Encomendero, Jimy DeJarld, Matthew T. Tahhan, Maher B. Chumbes, Eduardo M. Laroche, Jeffrey R. Jena, Debdeep Xing, Huili G. Choi, Sukwon The Pennsylvania State University Department of Mechanical Engineering University ParkPA16082 United States Cornell University School of Electrical and Computer Engineering Department of Materials Science and Engineering IthacaNY14850 United States Raytheon Advanced Microelectronics Solutions AndoverMA01810 United States Raytheon Advanced Technologies TewksburyMA01876 United States

AlN/GaN/AlN high electron mobility transistors (HEMTs) offer enhanced carrier confinement and higher breakdown voltage than conventional AlGaN/GaN HEMTs. In this work, Raman thermometry was used to characterize the self-heating behavior of a single-finger AlN/GaN/AlN HEMT on 6H-SiC. A 3D finite element analysis model was created to optimize the thermal design of the device structure. Simulation results reveal that the optimal buffer layer thicknesses to minimize the channel temperature rise of AlN/GaN/AlN HEMTs on 6H-SiC and diamond substrates are ∼2 μm and ∼0.7 μm, respectively. Moreover, diamond substrate integration further enhances the thermal performance, achieving a ∼45% and ∼53% reduction in the device thermal resistance as compared to those of an AlN/GaN/AlN HEMT on 6H-SiC and an AlGaN/GaN HEMT on 4H-SiC, respectively. © 1980-2012 IEEE.

关键词： Gallium nitride

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On the transferability of post-processing heat treatments designed for PBF-LB IN718 alloys to directed energy deposition specimens

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International Journal of Advanced Manufacturing Technology 2025年第7期137卷 3949-3965页

作者： Serrano-Munoz, Itziar Agudo Jácome, Leonardo Thompsom, Sean Schneider, Judy Unter den Eichen 87 BerlinD-12205 Germany Materials Science and Engineering Division Propulsion and Structures Technology Development Directorate FCDD-AMT-MPS HuntsvilleAL35808 United States Department of Mechanical and Aerospace Engineering University of Alabama in Huntsville HuntsvilleAL35899 United States

Many processes are being developed for metal additive manufacturing (AM) which vary by their heat source and feedstock. The use of directed energy deposition (DED) is growing due to its ability to build larger structures outside of a contained powder bed chamber. However, the only standard exclusively for post-build heat treatment of AM IN718 is ASTM standard F3055-14a, developed for powder bed fusion (PBF). This study evaluates the applicability of this current heat treatment standard to AM IN718 specimens produced using two methods of DED: laser-blown powder (LP)-DED and arc-wire (AW)-DED. Electron microscopy and X-ray diffraction techniques were used to characterize the specimens in the as-built condition and after the full heat treatment (FHT) specified in F3055. No evidence of remaining Laves phase was observed in the two DED specimens after the FHT. Yield strengths for the DED specimens were 1049 MPa for FHT AW-DED and 1096 MPa for LP-DED, higher than the minimum stated for PBF-LB IN718 of 920 MPa. The size, morphology, inter-spacing, and diffraction patterns of the γ´ and γ´´ strengthening precipitates are found to be similar for both DED processes. Differences were observed in the microstructure evolution where the F3055 heat treatments resulted in partial recrystallization of the grain structure, with a higher content of annealing twins observed in the AW-DED. These microstructural differences correlate with differences in the resulting elongation to failure. Thus, it is proposed that variations in heat treatments are needed for optimizing IN718 produced by different AM processes. © The Author(s) 2025.

关键词： After-heat treatment

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The Investigation of Microstructure and mechanical Property of Incorporation of Cerium Oxide to AA2219 Through Liquid Forging Technique

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Journal of The Institution of Engineers (India): Series D 2025年第1期106卷 9-17页

作者： Karthik, A. Karunanithi, R. Srinivasan, S.A. Kumareshbabu, S.P. Department of Mechanical Engineering B.S. Abdur Rahman Crescent Institute of Science and Technology Seethakathi Estate Vandalur Tamil Nadu Chennai600048 India Department of Aerospace Engineering B.S. Abdur Rahman Crescent Institute of Science and Technology Seethakathi Estate Vandalur Tamil Nadu Chennai600048 India Department of Metallurgical and Materials Engineering National Institute of Technology Tiruchirappalli Tanjore Main Road National Highway 67 Tamil Nadu Tiruchirappalli620015 India

In this study, an attempt is made to prepare aluminum metal matrix composites of AA2219 with varying reinforcement of weight percentages of cerium oxide (X = 0.5%, 1%, 1.5%, and 2%) by liquid metallurgy technique involving liquid forging operation. The incorporation of rare earth oxide to AA2219 through liquid forging technique offers excellent solubility of the solute atom along with near-net shape capability, higher materials property, and reduced porosity level when compared with conventional casting route. The reinforcement of cerium oxide improves mobility, casting microstructure, reduces shrinkage and hot tearing tendency of AA2219. The AA2219 composites sample were casted at the following process parameter such as the applied pressure load 350 MPa, the heating die temperature 200 °C, melt temperature 750 °C, and 60 s dwell time. The main objective was to determine the effect of CeO2 particles on the microstructure and mechanical properties of AA2219 composites through liquid forging technique. X-ray diffraction studies revealed the presence of intermetallic phase present in the composites and the presence of CeO2 confirmed by EDS analysis. Scanning electron microscopy images showed a homogeneous distribution of CeO2 particles within the matrix and the grain boundaries. The reinforcement of CeO2 increase hardness of the composites with a maximum hardness of 123 VHN observed for 2 wt% CeO2 with AA2219. The tensile test indicated the significant effect of the CeO2 particles with an ultimate tensile strength of 232 MPa and 87 MPa yield strength when compared to the unreinforced material was around 130 Mpa and 75 MPa, respectively. Fractography showed ductile fracture mode failure and the increase in CeO2 decrease the level of strain rate. © The Institution of Engineers (India) 2020.

关键词： Microstructure

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High cycle fatigue performance at 650℃and corresponding fracture behaviors of GH4169 joint produced by linear friction welding

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Chinese Journal of Aeronautics 2025年第1期38卷 622-637页

作者： Shitong MA Xiawei YANG Zhenguo GUO Yu SU Xinyuan HE Ju LI Jun TAO Bo XIAO Wenya LI State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology InstituteBeijing 100024China Department of Mechanical Engineering City University of HongKongHongKongChina

GH4169 joints manufactured by Linear Friction Welding(LFW)are subjected to tensile test and stair-case method to evaluate the High Cycle Fatigue(HCF)performance at 650℃.The yield and ultimate tensile strengths are 582 MPa and 820 MPa,*** HCF strength of joint reaches 400 MPa,which is slightly lower than that of Base Metal(BM),indicating reliable quality of this type of *** microstructure observation results show that all cracks initiate at the inside of specimens and transfer into deeper region with decrease of external stress,and the crack initiation site is related with microhardness of *** Electron Backscattered Diffraction(EBSD)results of the observed regions with different distances to fracture show that plastic deformation plays a key role in HCF,and the Schmid factor of most grains near fracture exceeds *** addition,the generation of twins plays a vital role in strain concentration release and coordinating plastic deformation among grains.

关键词： High cycle fatigue GH4169 superalloy Linear friction welding Fracture mechanism Microstructure evolution

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Effects of La and Ce on the microstructure,thermal conductivity and strength synergy of the as-extruded Mg-Mn-RE alloys

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Journal of Magnesium and Alloys 2025年第2期13卷 654-667页

作者： Huafeng Liu Taiki Nakata Chao Xu Guangze Tang Danyang Li Xiaojun Wang Guisong Wang Shigeharu Kamado Lin Geng State Key Laboratory of Precision Welding&Joining of Materials and Structures Harbin Institute of TechnologyHarbin150001PR China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001PR China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka940-2188Japan Laboratory for Space Environment and Physical Sciences Harbin Institute of TechnologyHarbin150001PR China School of Physics Harbin Institute of TechnologyHarbin150001PR China

High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabricated via hot *** effects of La and Ce additions on the microstructure,thermal conductivity,and mechanical properties of the Mg-1.5Mn alloy were *** results indicated that both the as-extruded Mg-1.5Mn-2.5La and Mg-1.5Mn-2.5Ce alloys exhibited a bimodal grain structure,with dynamically precipitated nano-scaleα-Mn *** comparison with La,the addition of Ce enhanced the dynamic precipitation more effectively during hot extrusion,while its influence on promoting the dynamic recrystallization was relatively *** high tensile strength obtained in the as-extruded Mg-1.5Mn-2.5RE alloys can be attributed to the combined influence of the bimodal grain structure(with fine dynamic recrystallized(DRXed)grain size and high proportion of un-dynamic recrystallized(unDRXed)grains),dense nano-scale precipitates,and broken Mg12RE phases,while the remarkable thermal conductivity was due to the precipitation of Mn-rich phases from the Mg matrix.

关键词： Mg-Mn-RE alloys Thermal conductivity mechanical properties Dynamic precipitation

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Microstructure—Property Relations in a Hydraulically Pressed and Machined Medium Carbon Low Alloy Quenched and Partitioned Steel 2nd

Microstructure—Property Relations in a Hydraulically Presse...

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2nd International Conference on mechanical engineering, INCOM 2024

作者： Verma, Rajan Kumar Ranjan, Ravi Ghosh, Chiradeep Kumar, Vidyapati Anand, Gautam Dutta, Monojit Research and Development and Scientific Services Tata Steel Limited Jamshedpur831001 India Department of Mechanical Engineering Indian Institute of Technology Kharagpur Kharagpur721302 India Department of Metallurgy and Materials Engineering Indian Institute of Engineering Science and Technology Shibpur711102 India

ISBN: (纸本)9789819766666

Quenched and partitioned (QP) steels are advanced high-strength steels offering an optimal combination of strength and ductility for automotive structure applications. This study investigates the influence of hydraulic pressing and machining as processing routes to tailor the microstructure and mechanical properties of a medium carbon low-alloyed QP steel. Five processing conditions were tested: as-received, hydraulically pressed, hydraulically pressed and machined, machined only and no pressing/machining. Tensile testing revealed a substantial increase in ultimate tensile strength (16%) and total elongation (35%) for the hydraulically pressed sample compared to the as-received condition. The enhanced properties are attributed to work hardening and increased dislocation density introduced during pressing, which refined the martensite microstructure. Reducing thickness by machining also showed moderate improvements in elongation with a marginal drop in strength. The highest strength of 1923 MPa and elongation of ~ 11% was attained by the combination of hydraulic pressing and machining. Microhardness tests further corroborated the tensile trends, with the hydraulically pressed sample exhibiting the maximum hardness. The study demonstrates that tailored selection of processing techniques can effectively optimize the microstructure and performance of medium carbon QP steels. The results provide critical insights into the microstructure-property relationships in these steels and guidance for achieving the desired strength-ductility balance for structural applications. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Ductility

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Diffusioosmotic Reversal of Colloidal Focusing Direction in a Microfluidic T-Junction

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Physical Review Letters 2025年第9期134卷 098201-098201页

作者： Haoyu Liu Amir A. Pahlavan Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06511 USA

Solute gradients next to an interface drive a diffusioosmotic flow, the origin of which lies in the intermolecular interactions between the solute and the interface. These flows on the surface of colloids introduce an effective slip velocity, driving their diffusiophoretic migration. In confined environments, the interplay between diffusiophoresis and diffusioosmosis governs the motion of colloids. Previous studies have indeed demonstrated the quantitative modulation of phoretic migration by the osmotic flows. Here, we show that diffusioosmotic flows can lead to qualitatively distinct outcomes, reversing the direction of colloidal focusing expected from diffusiophoresis alone. Using microfluidic experiments in a T-junction, numerical simulations, and theoretical modeling, we explain our observations to be due to an interplay between diffusiophoretic migration of colloids toward the walls and their entrainment in a diffusioosmotic vortex. We show this focusing to be persistent for a range of salt types, salt gradients, and flow rates, and establish a criterion for its emergence. Our work sheds light on how boundaries modulate the solute-mediated transport of colloids in confined environments and how the colloidal trajectories can be utilized to infer the surface properties.

关键词： Focusing

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Impact of atomization methods on aluminum alloy powder characteristics and 3D printing performance in laser directed energy deposition process

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Transactions of Nonferrous Metals Society of China 2025年第4期35卷 1057-1074页

作者： Gang RUAN Yu-dong LIANG Gan LI Ying JIN Xing-gang LI Department of Mechanical and Energy Engineering Southern University of Science and Technology(SUSTech)Shenzhen 518055China Department of Materials Science and Engineering Southern University of Science and Technology(SUSTech)Shenzhen 518055China Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Zhejiang Yatong Advanced Materials Co. Ltd.Hangzhou 310030China

A comparative study on the performance of gas atomized(GA)and rotating-disk atomized(RDA)aluminum alloy powders produced on industrial scale for laser directed energy deposition(L-DED)process was carried *** powder characteristics,the printing process window,and the quality,microstructure,and mechanical properties of printed parts were taken into account for comparison and *** results demonstrate that the RDA powder is superior to the GA powder in terms of sphericity,surface quality,internal defects,flowability,and apparent density,together with a larger printing process window during the L-DED parts ***,the resultant parts from the RDA powder have higher dimensional accuracy,lower internal defects,more uniform and finer microstructure,and more favorable mechanical properties than those from the GA powder.

关键词： metal additive manufacturing rotating disk atomization gas atomization AlSi10Mg powder powder feedstocks

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Reduced erosion and its erosion reducing mechanism of gun propellants by octaphenylsilsesquioxane

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材料科学技术（英文版） 2025年第4期207卷 86-94页

作者： Taixin Liang Jiaxin Lu Fei Xiao Hua Guo Chunzhi Li Mukun He Baosheng Liu Zeinhom M.El-Bahy Nawaa Ali H.Alshammari Xin Liao Salah M.El-Bahy Zhongliang Xiao Zhanhu Guo School of Environment and Safety Engineering North University of ChinaTaiyuan 030051China School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China Luzhou North Chemical Industries Co. LTDLuzhou 646000China School of Environment and Safety Engineering North University of ChinaTaiyuan 030051China Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi'an 710072China Luzhou North Chemical Industries Co. LTDLuzhou 646000China College of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China Department of Chemistry Faculty of ScienceAl-Azhar UniversityNasr City 11884CairoEgypt Department of Chemistry Faculty of ScienceNorthern Border UniversityArar 73222Saudi Arabia School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China Department of Chemistry Turabah University CollegeTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Department of Mechanical and Civil Engineering Faculty of Engineering and EnvironmentNorthumbria UniversityNewcastle Upon TyneNE1 8STUK

Low erosion high-energy propellant is one of the research directions to extend the weapon's life and improve the weapon's *** this study,energetic propellants containing different corrosion in-hibitors were designed and *** bomb tests and semi-confined bomb experiments were used to investigate the burning and erosion properties of the *** mechanism of erosion-reducing of titanium dioxide(titania,TiO2),talc,and octaphenylsilsesquioxane(OPS)on the propellant was com-paratively *** results show that OPS has the lowest burning rate and the longest burning time,and a minimized loss of fire force,with the best effect of explosion heat *** erosion reduction efficiency of OPS is twice that of TiO2 and *** mechanism analysis shows that the decomposition and heat absorption of OPS can effectively reduce the thermal erosion effect and carbon erosion,and the gas produced can reduce the loss of chamber pressure and form a uniformly distributed nano-SiO2 protective *** solid-state high-efficiency organosilicon erosion inhibitor is an important guide for designing high-energy low-erosion gun propellants.

关键词： Octaphenylsilsesquioxane Propellant Erosion inhibitors High efficiency

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不锈钢-铜复合箔材微拉深成形性能的模拟和实验研究（英文）

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Journal of Central South University 2025年第04期32卷 1237-1251页

作者：齐艳阳马晓光姜正义马丽楠王志华周存龙 HASAN Mahadi DOBRZA?SKI Leszek A. 赵敬伟 College of Mechanical Engineering Taiyuan University of Technology Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment(Ministry of Education) School of Mechanical Materials Biomedical and Mechatronic Engineering University of Wollongong School of Mechanical Engineering Taiyuan University of Science and Technology Department of Industrial and Production Engineering American International University Bangladesh Medical and Dental Engineering Center for Research Design and Production ASKLEPIOS

在本研究中，将厚度为50μm的双层不锈钢-铜复合箔材分别在800、900和1000℃下退火5 min，以获得不同的微观组织结构。研究退火温度对不锈钢-铜复合箔材成形性能和微拉深件表面质量的影响，并分析了其成形机制，开发了基础模型、Vorono... 详细信息

在本研究中，将厚度为50μm的双层不锈钢-铜复合箔材分别在800、900和1000℃下退火5 min，以获得不同的微观组织结构。研究退火温度对不锈钢-铜复合箔材成形性能和微拉深件表面质量的影响，并分析了其成形机制，开发了基础模型、Voronoi模型和表面形貌模型用于分析不锈钢-铜复合箔材微拉深过程中的成形性能。结果表明，900℃退火的不锈钢-铜复合箔材的微观组织均匀且细化，因而表现出最佳的塑性。在微拉深过程中，拉深力随退火温度的升高而降低。900℃退火试样成形的微拉深件起皱较少，壁厚分布较均匀，表面质量较高。与基础模型和Voronoi模型相比，考虑材料不均匀性和表面形貌的表面形貌模型与实验结果最接近。

关键词：微拉深退火温度不锈钢-铜复合箔材成形性能起皱有限元方法

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