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Ultrasonic excitation induced nanocrystallization and toughening of Zr46.75Cu46.75Al6.5 bulk metallic glass

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Journal of Materials Science & technology 2020年第10期42卷 157-161页

作者： W.Zhai l.h.Nie X.D.hui Y.Xiao t.Wang B.Wei School of Physical Science and technology Northwestern Polytechnical UniversityXi'an 710072China State Key laboratory for Advanced Metals and Materials University of Science&Technology BeijingBeijing 100083China

Intensive power ultrasound is introduced to Zr46.75Cu46.75Al6.5bulk metallic glass(BMG)as an easy-procurable,non-destructive physical method to modulate its atomic rearrangement and shear deformation *** microstructure after ultrasonic excitation with amplitude about 15μm in 20 k hz for 2 h is characterized by large amount of Cu10Zr7 nanocrystals with size of 20–50 nm embedded in the glass *** leads to a sharp increase in the critical stress for the first pop-in event of shear banding,and thus simultaneously improves both compressive plasticity and yield *** findings provide a novel approach for overcoming the strength-ductility trade-off dilemma.

关键词： Bulk metallic glass Nanocrystallization Plasticity toughness Ultrasound

StUDY OF tCP PhASE PRECIPItAtING IN Gh4199 SUPERAllOY

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Acta Metallurgica Sinica(English letters) 2004年第5期17卷 645-650页

作者： t.Cui Y.S.Zhang S.W.Guo l.Wang h.C.Yang SchoolofMaterialsandMetallurgy NortheasternUniversityShenyang110004ChinaManuscriptreceived15July2003 inrevisedform19January2004

the precipitating regulation and mechanism of tCP phase (μ phase and σ phase) are studied, using electron hole number (EhN) theory, phase analysis technology and tEM observation. the results indicate that the EhN in studied alloy is 2.311-2.348 which is higher than that of critical EhN of μ phase precipitate (2.30), so μ phase could precipitate if there is enough thermo-exposition. In contrast, the calculated EhN is less than that of critical EhN of σ phase precipitate (2.52). however the σ phase is also observed by tEM. Enrich of Cr and Mo around γ phase after γ′phase precipitated leads to σ phase precipitated.

关键词： superalloy tCP phase electron hole number

Dynamic mechanical relaxation behavior of Zr_(35)hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass

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Journal of Materials Science & technology 2021年第24期83卷 248-255页

作者： l.t.Zhang Y.J.Duan t.Wada h.Kato J.M.Pelletier D.Crespo E.Pineda J.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China Institute for Materials Research Tohoku UniversitySendai980-8577Japan Universitéde lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621Villeurbanne CedexFrance Department of Physics Barcelona Research Center in Multiscale Science and TechnologyInstitute of Energy TechnologiesUniversitat Politècnica de Catalunya08019BarcelonaSpain

Non-equiatomic high entropy bulk metallic glasses were reported recently and show unique mechanical and physical *** mechanical relaxation behavior of Zr_(35)hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass was investigated by dynamic mechanical analysis(DMA)and the mechanical spectra could be well described by the quasi-point defects(QPD)*** to typical metallic glasses,the intensity of theβrelaxation of Zr_(35)hf_(17.5)ti_(5.5)Al_(12.5)Co_(7.5)Ni_(12)Cu_(10)high entropy bulk metallic glass is lower due to the sluggish *** the same time,the correlation factor is higher than that of conventional metallic glasses and this is ascribed to the high configuration *** parallel,physical aging below the glass transition temperature leads to a decrease of atomic mobility,caused by a decrease of the concentration of defects.

关键词： high entropy bulk metallic glass Mechanical relaxation Quasi-point defects Physical aging

Evaluation of the virulence of entomopathogenic fungus, Isaria fumosorosea isolates against subterranean termites Coptotermes spp.(Isoptera:Rhinotermitidae)

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Journal of Forestry Research 2019年第1期30卷 213-218页

作者： J.J.Jessica t.l.Peng A.S.Sajap S.h.lee S.A.Syazwan Department of Forest Management Faculty of ForestryUniversiti Putra Malaysia (UPM) Faculty of Veterinary Medicine University Malaysia Kelantan Institute of tropical Forestry and Forest Products Universiti Putra Malaysia (UPM) Mycology and Pathology laboratory Forest Biodiversity Division Forest Research Institute Malaysia

the entomopathogenic fungus Isaria fumosorosea Wize, formerly known as Paecilomyces fumosoroseus is reported as a promising biocontrol agent for controlling subterranean termites, particularly those belonging to the family Rhinotermitidae. In Malaysia, the family Rhinotermitidae includes two species of subterranean termites with extremely high economic importance; namely Coptotermes curvignathus holmgren, and the Asian Slubterranean termite (Coptotermes gestroi Wasmann). to comprehend the potential control of this soil-dwelling fungus against these subterranean termites in Malaysia, an investigation was carried out by testing the pathogenecity of 11 isolates against these termite species. All isolates showed pathogenic potential against the termite (Mortality rate of C. curvignathus:84.4%; C. gestroi:67.3%). IsolatePF49 was the most effective against both species of termites and was further tested for its virulence and *** lC_(50) values of PF49 against C. curvignathus and *** were 7.55×103 and 1.09×102 conidia/ml,respectively. the average number of days required to complete the mycosis process in C. curvignathus and *** were 4.7 and 8 days, respectively. these fungi are believed useful for protecting living trees, plants, wood,wood structures, and other cellulosic materials susceptible to termite infestation and damage.

关键词： Biological control Entomopathogenic fungus Subterranean termites lethal concentration

An Experimental Investigation on the Drying of Sliced Food Products in Centrifugal Fluidized Bed

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Journal of thermal Science 1998年第3期7卷 181-185页

作者： M.h.Shi Y.l.hao Y.t.Din DepartmentofPowerEngineering SoutheastUniversityNanjing210096ChinaDepartmentofPowerEngineeringSoutheastUniversityNanjing210096ChinaDepartmentofPowerEngineeringSoutheastUniversityNanjing210096China

An experimental investigation on the fluidization and drying characteristics of sliced food products in a centrifugal fluidized bed dryer was carried out. the rotating speed ranges from 300 rpm to 500 *** potato and radish were used as the testing materials. the results show that the sliced materials can be fluidised well in the centrifugal fluidized bed. the fiuidized curve has a maximum value and the critical fiuidised velocities Vary with the type of the test material, its shape and dimension as well as operating parameters. the sliced food materials can be dried very well and fast in the ceotrifugal fiuidised bed with a large productivity. the factors that influence the drying process were examined and discussed. the final shape and inner structure of the dried products were *** water recovery characteristics of the dried products were also investigated.

关键词： drying rewet sliced product centrifugal fluidized bed

Analysis of the anelastic deformation of high-entropy Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) metallic glass under stress relaxation and recovery

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Journal of Materials Science & technology 2022年第12期107卷 82-91页

作者： Y.J.Duan l.t.Zhang t.Wada h.Kato E.Pineda D.Crespo J.M.Pelletier J.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Department of Physics Institute of Energy TechnologiesUniversitat Politècnica de CatalunyaBarcelona 08019Spain Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Universitéde lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonF-69621 Villeurbanne CedexFrance

the anelastic deformation behavior of Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass was probed by monitoring the stress relaxation and recovery processes. the stress relaxation under consecutive strain steps can be described by the Kohlrausch-williams-Watts(KWW) function. In addition, considering a hierarchy of relaxation processes related to the structural heterogeneity, a constitutive model is proposed in order to describe the whole process of stress relaxation and determine the contribution of different time scales. Moreover, a crossover from stochastic activation to percolation of flow defects with the ultimate strain can be observed during stress relaxation process. the anelastic recovery process after a strain step is studied as a function of the initial strain level and characterized by means of a direct spectrum analysis. the peaks in the recovery time-spectra revealed the evolution of flow defects in Pd_(20)Pt_(20)Cu_(20)Ni_(20)P_(20) high-entropy metallic glass. the understanding of the atomic free-volume zones effect and the anelastic deformation provides important insight into how atomic structural features affect the deformation behavior of high-entropy metallic glasses, and may provide a new avenue into the improvement of their mechanical properties.

关键词： high-entropy metallic glass Stress relaxation Anelastic deformation Flow defects Free-volume zones

Effects of varying Alx moles on structure and luminescence properties of ZnAl_(x)O_(1.5x+1):0.1 mol%tb^(3+)nanophosphors prepared using citrate sol-gel method

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Journal of Rare Earths 2023年第3期41卷 358-364,I0002页

作者： V.M.Maphiri l.t.Melato M.R.Mhlongo t.t.hlatshwayo t.E.Motaung l.F.Koao S.V.Motloung Department of Physics Sefako Makgatho Health Science UniversityP.O.Box 94Medunsa0204South Africa Department of Mathematics Non Destructive Testing and PhysicsVaal University of TechnologyAndries Potgieter BlvdVanderbijlpark1900South Africa Department of Physics University of PretoriaPretoria0002South Africa Department of Chemistry School of Science in the College of Science Engineering and TechnologyUniversity of South AfricaPreller StreetMuckleneuk RidgeCity of TshwaneP.O Box 392UNISA 0003South Africa Department of Chemistry Sefako Makgatho Health Science UniversityP.O.Box 94Medunsa0204South Africa Department of Physics University of the Free State(Qwaqwa Campus)Private Bag X13Phuthaditjhaba 9866South Africa Department of Chemical and Physical Sciences Walter Sisulu UniversityMthathaSouth Africa

Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%tb^(3+)(ZAOt)nano-powders were synthesized via citrate sol-gel *** AIx moles were varied in the range of 0.25≤x≤*** X-ray powder diffraction(XRD)data reveal that for xthe prepared samples crystal structure consists of mixed phases of the cubic ZnAl_(2)O_(4) and hexagonal ZnO phases,while for x>1.5 the structure consists of single phase of cubic ZnAl_(2)O_(4).the Raman and Fourier-trans form infrared(FtIR)vibrational spectroscopy show the presence of vibrations emanating ZnAl_(2)O_(4) *** electron microscopy(SEM)and transmission electron microscopy(tEM)show the presence of irregular sphere at x>2.0 attributed to ZnAl_(2)O_(4).the photoluminescence(Pl)spectroscopy reveals emissions from both the host and tb^(3+)*** from tb^(3+)are observed at 382,414,439,458 nm and 489,545,585,621 nm,which were attributed to the^(5)D_(3)→^(7)F_(6,5,4,2) and ^(5^)D_(4)→^(7)F_(6,5,4,3),*** results confirm that the tb^(3+)occupation site depends on the Alx *** International Commission on Illumination(CIE)colour chromaticity shows that the emission colour can be tuned from blue to green by varying the AIx moles.

关键词： Citrate sol-gel ZnAl_(2)O_(4)/ZnO tb^(3+)-doped Al_(x)moles Photoluminescence Rare earths

Achieving ultrahigh strength and ductility in high-entropy alloys via dual precipitation

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Journal of Materials Science & technology 2023年第35期166卷 67-77页

作者： J.M.Guo B.C.Zhou S.Qiu h.J.Kong M.C.Niu J.h.luan t.l.Zhang h.Wu Z.B.Jiao Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong KongChina the hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China Department of Materials Science and Engineering City University of Hong KongHong KongChina State Key laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

the strength-ductility trade-offhas been a longstanding dilemma in metallic *** we report an innovative approach to achieve a high strength-ductility synergy via dual precipitation of sheared and bypassed precipitates.(Ni_(2) Co_(2) FeCr)_(96-x) Al_(4) Nb_(x)(at.%)alloys strengthened by nanoscale l12 particles and laves precipitates were selected as a model for this study,and their precipitate microstructures and mechanical properties were thoroughly *** dual-precipitation-strengthened alloys exhibit a yield strength of more than 1400 MPa,an ultimate tensile strength of over 1800 MPa,and a uniform elon-gation of 18%,thus achieving a high strength-ductility *** analysis reveals that the nanoscale l1_(2) precipitates contribute to the strength via the particle shearing mechanism,whereas the laves phase provides the strengthening through the Orowan bypass *** study of deformation microstruc-tures shows that the l1_(2) precipitates are sheared by stacking faults,which facilitates long-range disloca-tion gliding through the *** a result,deformation induces the formation of hierarchical stacking fault networks and immobile lomer-Cottrell locks,which effectively enhance the work hardening ca-pability and plastic stability,thereby resulting in a high ductility at high strength *** are piled-up against the interface between the laves precipitates and matrix,which increases the work hardening capability at the early stages of plastic deformation but causes stress *** dual precipitation strategy may be useful for many other alloys for achieving superior mechanical properties for technological applications.

关键词： high-entropy alloy Dual precipitation Precipitation strengthening Deformation mechanism

煤中惰质组及其古环境意义:来自AI和大数据分析的启示

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中国科学：地球科学 2024年第6期54卷 1806-1829页

作者：邵龙义周家民 timothy P.JONES 华芳辉徐小涛闫志明侯海海王东东鲁静中国矿业大学(北京)煤炭精细勘探与智能开发全国重点实验室中国矿业大学(北京)地球科学与测绘工程学院北京100083 School of Earth and Environmental Sciences Cardiff UniversityCardiffCF103YEWalesEngland 中国煤炭地质总局勘查研究总院北京100039 潍坊学院土木与交通学院潍坊261061 辽宁工程技术大学矿业学院阜新123000 山东科技大学地球科学与工程学院青岛266590

惰质组是煤中常见且重要的显微组分组,作为古野火指示物在古环境研究中发挥着至关重要的作用,古野火在多种生态系统中扮演着不可替代的角色.通过惰质组来讨论古野火与古气候变化及古植物演化的研究逐年增多.丝质体和半丝质体的反射率可... 详细信息

惰质组是煤中常见且重要的显微组分组,作为古野火指示物在古环境研究中发挥着至关重要的作用,古野火在多种生态系统中扮演着不可替代的角色.通过惰质组来讨论古野火与古气候变化及古植物演化的研究逐年增多.丝质体和半丝质体的反射率可以用来估算古野火的燃烧温度及类型,进而判断不同类型野火的燃烧特征.惰质组的相对丰度可以重建大气氧含量.人工智能(AI)和科学数据库的在线搜索工具的快速发展,使得查找、收集、整理和分析从最老到最新的出版物,以及出版物中的全球惰质组数据成为可能.本文使用数据提取工具Deep Shovel收集分析从志留纪到新近纪的全球惰质组数据,然后应用Gplates、ArcGIS pro、tableau等多个软件建立地质历史时期惰质组相对丰度的变化模型,该模型可以与其他因素如大气氧含量、植物进化及古气候变化等进行关联.惰质组在地质历史中的分布特征差异很大,二叠纪属于典型的“高惰质组含量-高大气氧含量”时期,新生代属于典型的“低惰质组含量-低大气氧含量”时期.本文提出惰质组特征与古环境因素之间的可能性正负反馈关系,揭示出惰质组在地质古环境演化研究中发挥着不可替代的作用.未来惰质组相关研究应该聚焦在有机岩石学和有机地球化学的深入结合,大数据驱动的惰质组时、空分布特征,古野火在不同气候背景下的地球系统中发挥的作用以及融合现代野火研究预测未来由于气候变化导致的野火发生的频率和强度.

关键词：惰质组古野火大气氧含量古气候古生态系统