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Sparse identification-assisted exploration of the atomic-scale deformation mechanism in multiphase CoCrFeNi high-entropy alloys

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science china(Technological sciences) 2024年第4期67卷 1124-1132页

作者： XIAO Lu guo xiaoxiang SUN YuTong wang Gang LONG WeiMin LIAW Peter K. REN JingLi school of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China Academy of Mathematics and Systems science Chinese Academy of SciencesBeijing 100190China Institute of materials Shanghai UniversityShanghai 200444China SKL of Advanced Brazing Metals&Technology Zhengzhou Research Institute of Mechanical EngineeringZhengzhou 450001China Department of materials science and engineering The University of TennesseeKnoxvilleTN 37996USA

This study investigated the atomic-scale deformation mechanism of multiphase CoCrFeNi high-entropy alloys(heAs)at liquid helium,liquid nitrogen,and room temperatures.A million-atom multiphase heA was prepared using molecular dynamics simulation involving melt and quench *** heA exhibited high-density dislocations and some twins,consistent with experimental *** analysis revealed an inconsistent evolution of the microstructure under tensile *** particular,the elastic and initial plastic stages exhibited an increase in the disordered structure at the expense of the face-centered cubic and hexagonal close-packed structures,followed by a subsequent transformation involving multiple structural ***,through sparse identification,a model depicting microstructural evolution during tension was extracted for the CoCrFeNi heA at three typical temperatures and three tensile *** model highlighted the importance of the body-centered cubic structure in the evolutionary process.

关键词： high-entropy alloy data-driven method microstructure evolution multiphase structure molecular dynamics simulation

Preparation of Superfine-Cemented Carbide by Spark Plasma Sintering

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Journal of Wuhan university of Technology(materials science) 2006年第1期21卷 42-45页

作者：解迎芳王兴庆 school of materials science and engineering Shanghai University Shanghai 200072 China

92WC-8Co puwder mixture with superfine-tungsten carbide was respectively sintered by spark plasma sintering（ SPS ） and sintering isostutic pressure （SIP）. Complete dense samples with 200 nm WC grains and 94.2HRA hardness were prepared by spark plasma sintering at 1 150 ℃ and under 4.5 kN for 5 minutes. SIP was carried out at 1 400 ℃ for 30 minutes with a result of 300-400 nm WC grains and 93 HRA hardness. The results show that sintering temperature is greatly decreased by SPS, sintering time is largely shortened and WC grain growth is effectively retarded. Micropores and drawb（wks in superfine-cemented carbide made by SPS are greatly declined, which is very useful to improving nwehanical properties.

关键词： spurk plasma sintering cemented carbide superfine grain sintering mechanism

Sintering of WC-Co powder with nanocrystalline WC by spark plasma sintering

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Rare Metals 2006年第3期25卷 246-252页

作者： wang xingqing XIE Yingfang guo hailiang O.Van der Biest J.Vleugels school of materials science and engineering Shanghai University Shanghai 200072 China materials engineering Faculty of engineering Katholikeke Universiteit Leuven Leuven 3000 Belgium

A 92WC-8Co powder mixture with 33 nm WC grains was prepared by strengthening ball milling and was then sintered by spark plasma sintering （SPS） at 1000-1200℃ for 5-18 rain under 10-25 kN, respectively. Movement of the position of low punch shown shrinkage of the sintered body began above 800℃. The shrinkage slowly rose as the temperature rose from 800 to 1000℃ and then quickly rose at above 1000℃ and then gradually rose at above 1150℃. The densities of the samples increased with an increase in sintering temperature, rapidly below 1100℃, and then gradually above 1100℃. WC grains grow gradually with increasing sintering temperature. The powder was sintered to near full density at 1100℃ for 5 rain under 10 kN. The best result of the sample with 275 nm WC grains and no pores was obtained at 1150℃ under 10 kN for 5 rain. The research found the graphite die had a function of carburization, which could compensate the sintered body for the lack of carbon, and had the normal microstructure.

关键词： nanocrystalline cemented carbide spark plasma sintering low temperature sintering strengthening ball milling

Correlation between jerky flow and jerky dynamics in a nanoscratch on a metallic glass film

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science china(Physics,Mechanics & Astronomy) 2020年第7期63卷 89-92页

作者： LiPing Yu DongXue Han JingLi Ren xiaoxiang guo ShaoKang Guan Gang wang henan Academy of Big Data Zhengzhou University.Zhengzhou 450052China College of science Henan University of TechnologyZhengzhou 450001China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai 200444China school of materials science and engineering Zhengzhou UniversityZhengzhou 450001China

Chaos has been well understood in dynamic system, however, how the chaotic behavior occur in jerky flow in material, is still not clear, and is lack of specific chaotic attractor. here the jerky evolution of lateral force and the stair-like fluctuation of lateral displacement are observed for Ni62 Nb38(at.%) metallic glass film during nanoscratch process. This jerky flow is investigated by using the largest Lyapunov exponent, Kolmogorov entropy and fractal dimension, and chaotic behavior of lateral force-time and normal displacement-lateral displacement sequences is verified. In addition to time series analysis, it is found that jerk equation can be used to describe the jerky flow of the metallic-glass film during nanoscratch. More importantly, unambiguous chaotic attractor is presented by jerky dynamics using "jerk"-singularities, namely the total change rate of lateral force relative to scratch time. These reveal an inner connection between jerky flow and jerky dynamics in nanoscratch of a metallic-glass film.

关键词： metallic-glass film jerky flow jerky dynamics chaos