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A room-temperature magnetic semiconductor from a Co-Fe-Nb-B metallic glass

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science China(Physics,Mechanics & Astronomy) 2023年第4期66卷 94-99页

作者： Yu-Zhang Jiao Dmitry VLouzguine-Luzgin Ke-Fu Yao Zheng-Jun Zhang Na Chen Laboratory for advanced Materials Processing technology(MOE) State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for advanced Materials(MOE) Schoolof Materials Science and EngineeringTsinghua UniversityBeijing 100084China advanced institute for Materials research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan Mathematics for advanced Materials-OIL National Institute of Advanced Industrial Science and Technology(AIST)Sendai 980-8577Japan

Magnetic semiconductors with Curie temperatures higher than room temperature show potential for developing spintronic devices with combined data processing and storage functions for next-generation computing *** this study,we present an n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3) magnetic semiconductor with a high Curie temperature of~559 *** magnetic semiconductor has a room-temperature resistivity of~2.10×10^(4)Ωcm and a saturation magnetization of~76 emu/cm^(3).The n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3)magnetic semiconductor was deposited on p-type silicon to form a heterojunction,exhibiting a rectifying *** results provide the design principles for discovering high Curie temperature magnetic semiconductors with determined conduction types,which would play an essential role in realizing nonvolatile spin-based transistors that break free from the confines of currently established Si-based information technology.

关键词： magnetic semiconductor ferromagnetic metallic glass high Curie temperature

Solid-State Interfacial Reaction between Eutectic Au-Ge Solder and Cu/Ni(P)/Au Metalized Ceramic Substrate and Its Suppression

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Journal of Materials science & technology 2015年第5期31卷 445-452页

作者： F.Q.Lang H.Yamaguchi H.Nakagawa H.Sato advanced Power Electronics research Center(ADPERC) National Institute of Advanced Industrial Science and Technology(AIST).Central 21-1-1UmezonoTsukubaIbaraki 305-8568.Japan

Eutectic Au-12 Ge solder was employed to bond the SiC power devices to a Si3N4/Cu/Ni（P）/Au multilayered *** high-temperature reliability of the bond was investigated in detail at 200,250,300 and 330 ℃,*** and Ni5Ge3intermetallic compounds（IMCs） were identified at the Au-12Ge/Ni（P） interface by micro X-ray diffraction（μXRD） and scanning electron microscopy（SEM）equipped with energy dispersive X-ray analysis（EDX）.The growth of the Ni-Ge IMCs was dominated by Ni5Ge3layer,which formed at the Ni5Ge3/NiGe interface by outward diffusion of Ni from the Ni（P） *** activation energy of the total Ni-Ge IMCs growth was 66 kJ/*** shear strength of the bond was tested at both 25 ℃ and the aging temperatures,*** shear strength decreased slightly after aging at 200 and 250 ℃.The shear strength tested at 250 ℃ was 46 MPa after aging at 250 ℃ for 3000 *** shear strength aged at 300 and 330 ℃ rapidly decreased with aging time due to the rapid growth of the *** slow down the interfacial reaction between the high temperature solder and the Ni（P）layer,an approximately 200 nm-thick Ta/TaN/Ta new diffusion barrier（DB） was deposited on the *** by transmission electron microscopy（TEM） equipped with EDX,reveals that the Ta/TaN/Ta DB was bonded well to the Ni（P） layer and the *** temperature storage test at 330 ℃ for1500 h reveals that the bond of the SiC devices maintained its high shear strength of approximately56 MPa without *** new DB effectively suppressed the interfacial reaction between the Au-12 Ge solder and the Ni（P） layer of the substrate.

关键词： High-temperature solder Interfacial reaction Activ

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

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International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 518-524页

作者： Jing Wang Min-xu Lu Lei Zhang Wei Chang Li-ning Xu Li-hua Hu institute for advanced Materials and technology University of Science and Technology Beijing Beijing 100083 China research institute of China national Offshore Oil Corporation Beijing 100027 China

To obtain high-quality dissimilar weld joints, the processes of metal inert gas （MIG） welding and tungsten inert gas （TIG） welding for duplex stainless steel （DSS） and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy （SEM）; the chemical compositions in different zones were detected by en- ergy-dispersive spectroscopy （EDS）; the mechanical properties were measured by microhardness test, tensile test, and impact test; the corro- sion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG weld- ing. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaC1 solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints pro- duced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS $31803 duplex stainless steel and low alloy steel in practical application.

关键词： dissimilar metals welds stainless steel alloy steel microstructure mechanical properties corrosion

Effect of Substrate and Annealing Temperatures on Mechanical Properties of Ti-rich NiTi Films

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Journal of Materials science & technology 2010年第11期26卷 961-966页

作者： A.Kumar S.K.Sharma S.Bysakh S.V.Kamat S.Mohan Defence Metallurgical research Laboratory Department of Instrumentation Indian Institute of Science Central Glass and ceramics research institute

The effect of substrate and annealing temperatures on mechanical properties of Ti-rich NiTi films deposited on Si （100） substrates by DC magnetron sputtering was studied by *** films were deposited at two substrate temperatures viz.300 and 400 ℃.NiTi films deposited at 300 ℃ were annealed for 4 h at four different temperatures,i.e.300,400,500 and 600 C whereas films deposited at 400 ℃ were annealed for 4 h at three different temperatures,i.e.400,500 and 600 ℃.The elastic modulus and hardness of the films were found to be the same in the as-deposited as well as annealed conditions for both substrate *** a given substrate temperature,the hardness and elastic modulus were found to remain unchanged as long as the films were ***,both elastic modulus and hardness showed an increase with increasing annealing temperature as the films become *** results were explained on the basis of the change in microstructure of the film with change in annealing temperature.

关键词： NiTi thin film Annealing Nanoindentation

The highest melting point material:Searched by Bayesian global optimization with deep potential molecular dynamics

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Journal of advanced ceramics 2023年第4期12卷 803-814页

作者： Yinan Wang Bo Wen Xingjian Jiao Ya Li Lei Chen Yujin Wang Fu-Zhi Dai Artificial Intelligence for science institute Beijing 100084China science and technology on advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China College of Computer science and technology Heilongjiang Institute of TechnologyHarbin 150001China institute for advanced ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of advanced Structural-Functional Integration Materials&Green Manufacturing technology Harbin Institute of TechnologyHarbin 150001China DP technology Bejing 100080China

The interest in refractory materials is increasing rapidly in recent decades due to the development of hypersonic ***,the substance that has the highest melting point(Tm)keeps a secret,since precise measurements in extreme conditions are overwhelmingly *** the present work,an accurate deep potential(DP)model of a Hf-Ta-C-N system was first trained,and then applied to search for the highest melting point material by molecular dynamics(MD)simulation and Bayesian global optimization(BGO).The predicted melting points agree well with the experiments and confirm that carbon site vacancies can enhance the melting point of rock-saltstructure *** solid solution with N is verified as another new and more effective melting point enhancing approach for HfC,while a conventional routing of the solid solution with Ta(e.g.,HfTa_(4)C_(5))is not suggested to result in a maximum melting *** highest melting point(~4236 K)is achieved with the composition of HfCo.638No.271,which is~80 K higher than the highest value in a Hf-C binary *** mechanism of the N addition is believed to be unstable C-N and N-N bonds in liquid phase,which reduces liquid phase entropy and renders the liquid phase less *** improved melting point and less gas generation during oxidation by the addition of N provide a new routing to modify thermal protection materials for the hypersonic vehicles.

关键词： melting point(T_(m)) carbides carbonitrides deep potential(DP) Bayesiannglobal optimization(BGO)

User-guided line abstraction using coherence and structure analysis

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Computational Visual Media 2017年第2期3卷 177-188页

作者： Hui-Chi Tsai Ya-Hsuan Lee Ruen-Rone Lee Hung-Kuo Chu Department of Computer science "National Tsing Hua University" Information and Communications research Laboratories Industrial Technology Research Institute

Line drawing is a style of image abstraction where the perceptual content of the image is conveyed using distinct straight or curved lines. However,extracting semantically salient lines is not trivial and mastered only by skilled artists. While many parametric filters have successfully extracted accurate and coherent lines, their results are sensitive to parameter choice and easily lead to either an excessive or insufficient number of lines. In this work, we present an interactive system to generate concise line abstractions of arbitrary images via a few user specified strokes. Specifically, the user simply has to provide a few intuitive strokes on the input images, including tracing roughly along edges and scribbling on the region of interest, through a sketching interface. The system then automatically extracts lines that are long,coherent and share similar textural structures to form a corresponding highly detailed line drawing. We have tested our system with a wide variety of images. Our experimental results show that our system outperforms state-of-the-art techniques in terms of quality and efficiency.

关键词： line abstraction interactive drawing coherence strokes structure strokes stroke matching

Dynamic recrystallization behavior and microstructural evolution of Mg alloy AZ31 through high-speed rolling

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Journal of Materials science & technology 2018年第10期34卷 1747-1755页

作者： Jeong Hun Lee Jong Un Lee Sang-Hoon Kim Seok Weon Song Chong Soo Lee Sung Hyuk Park Ulsan Regional Division Korea Institute of Industrial Technology School of Materials science and Engineering Kyungpook National University Technical research Laboratories POSCO Graduate institute of Ferrous technology Pohang University of Science and Technology

High-speed rolling （HSR） is known to improve the workability of Mg alloys significantly, which makes it possible to impose a large reduction in a single pass without fracture. In the present study, dynamic recrystallization （DRX） behavior and microstructural and textural variations of Mg alloy AZ31 dur-ing a HSR process were investigated by conducting rolling with different imposed reductions in the range of 20%-80% at a high rolling speed of 470 m/min and 400℃. High-strain-rate deformation during HSR suppresses dislocation slips but promotes twinning, which results in the formation of numer-ous twins of several types, i.e., {10-12} extension twins, {10-11} and {10-13} contraction twins, and {10-11}-{10-12} double twins. After twinning, high strain energy is accumulated in twin bands because their crystallographic orientations are favorable for basal slips, leading to subsequent DRX at the twin bands. Accordingly, twinning activation and twinning-induced DRX behavior play crucial roles in accommodating plastic deformation during HSR and in varying microstructure and texture of the high- speed-rolled （HSRed） sheets. Area fraction of fine DRXed grains formed at the twin bands increases with increasing rolling reduction, which is attributed to the combined effects of increased strain, strain rate, and deformation temperature and a decreased critical strain for DRX. Size, internal strain, and texture intensity of the DRXed grains are smaller than those of unDRXed grains. Therefore, as rolling reduction increases, average grain size, stored internal energy, microstructural inhomogeneity, and basal texture intensity of the HSRed sheets gradually decrease owing to an increase in the area fraction of the DRXed grains.

关键词： Magnesium alloy High-speed rolling Twinning Dynamic recrystallization Microstructure

Recent advances in heterogeneous catalytic conversion of glucose to 5-hydroxymethylfurfural via green routes

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science China Chemistry 2017年第7期60卷 870-886页

作者： Jianjian Wang Jinxu Xi Qineng Xia Xiaohui Liu Yanqin Wang Key Laboratory for advanced Materials Research Institute of Industrial Catalysis East China University of Science and Technology Division of Physical sciences and Engineering King Abdullah University of Science and Technology

With concerns of diminishing fossil fuel reserves and environmental deterioration, great efforts have been made to explore novel approaches of efficiently utilizing bio-renewable feedstocks to produce chemicals and fuels. 5-Hydroxymethylfurfural(HMF),generated from dehydration of six-carbon ketose, is regarded as a primary and versatile renewable building block to realize the goal of production of these high valued products from renewable biomass resources transformation. In this review, we summarize the recent advances via green routes in the heterogeneous reaction system for the catalytic production of HMF from glucose conversion, and emphasize reaction pathways of these reaction approaches based on the fundamental mechanistic chemistry as well as highlight the challenges(such as separation and purification of products, reusing and regeneration of catalyst, recycling solvent) in this field.

关键词： 5-hydroxymethylfurfural glucose heterogeneous catalysis green route

A Hybrid Joining technology for Aluminum/Zinc Coated Steels in Vehicles

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Journal of Materials science & technology 2010年第9期26卷 858-864页

作者： C.Y.Choi D.C.Kim D.G.Nam Y.D.Kim Y.D.Park School of Materials science and Engineering Pusan National UniversityBusan advanced Welding & Joining R&D Division institute of industrial technology Incheon Dongnam technology Service Division Korea Institute of Industrial TechnologyBusan Department of advanced Materials Engineering Dong-Eui UniversityBusan

Currently,in the automotive industry,joining of the aluminum alloys with the steel is a crucial problem to be *** joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical *** investigation was carried out to develop the hybrid joining process combining the resistance spot welding and *** this study,an attempt was made to apply hybrid process to the joining of dissimilar sheet metals,Al-Mg-Si（6000 series） alloy and low carbon steel *** process（resistance spot weld/brazing） using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and *** hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength,it was proved to have reasonable interfacial bond layer if the optimal process condition was applied.

关键词： Hybrid joining Aluminum alloy Steel Resistance welding Brazing