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Achieving superior performance in powder-metallurgy near-βtitanium alloy by combining hot rolling and rapid heat treatment followed by aging

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Journal of materials Science & Technology 2024年第4期171卷 24-36页

作者： Fucheng Qiu Tuo Cheng Yuchao Song Orest m.Ivasishin dmytro G.Savvakin Guangyu ma Huiyan Xu College of materials Science and Engineering Jilin UniversityChangchun 130025China International Center of Future Science Jilin UniversityChangchun 130025China G.V.Kurdyumov Institute for metal Physics KyivUkraine College of Biological and Agricultural Jilin UniversityChangchun 130025China

Heat treatment plays an important role in tailoring the mechanical properties of powder-metallurgy(Pm)titanium ***,only limited work about the rapid heat treatment(RHT)of Pm titanium alloys has been *** this work,RHT was applied to Pm Ti-5Al-5mo-5V-1Cr-1Fe alloy after hot rolling to study the evolution of its mechanical properties and the influence of residual pores on its *** hot rolling and annealing,a fine and uniformα+βstructure with few residual pores is *** RHT,the primaryαdissolves gradually and completes in theβregion,and theβgrains then grow,resulting in the continuous decrease in elongation after ***,the tensile strength first increases and then decreases with increasing RHT temperature,owing to the increase in volume fraction of secondaryαinα+βregion and theβgrain growth inβ*** contrast to the RHT of cast-and-wrought titanium,the negative influence of residual pores lowers the RHT temperature for obtaining the highest tensile strength to a temperature below theβ-transus *** the negative influence of the residual pores,retained primaryαand fineβgrains with fine secondaryαinside contribute to achieving a good strength/ductility balance(1570 mPa and 6.1%,respectively).Addi-tionally,although at higher cycles to failure,the negative influence of residual pores increases as it affects the crack initiation zone at the subsurface,the good resistance of secondaryαto fatigue crack propaga-tion still enhances the fatigue strength considerably(about 300 mPa).This work suggests a cost-effective strategy to produce titanium alloys with high performance.

关键词： Rapid heat treatment Powder metallurgy mechanical properties Near-βtitanium Residual pores

Electrocatalytic performance of CNTs/graphene composited rare earth phthalocyanines(m=La,Y,Yb,Sc)

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Journal of Rare Earths 2024年第2期42卷 323-333,I0004页

作者： Tingting Jiang Caixia Ou Luyi Wang Jun Chen Sydorov dmytro Qian Zhang Jintian Luo Hua Wang Jiangxi Key Laboratory of Power Batteries and materials Faculty of Materials Metallurgy and ChemistryJiangxi University of Science and TechnologyGanzhou341000China Joint Department of Electrochemical Energy Systems Institute of Bioorganic Chemistry and PetrochemistryNational Academy of Sciences of Ukraine38A VernadskyAveKiev03142Ukraine Guangdong Jiana Energy Technology Co. Ltd.Qingyuan511500China

In this study,a class of rare earth composite sandwich phthalocyanines(mPcs,m=La,Y,Yb,Sc) were prepared and compounded with graphene and carbon nanotubes to obtain mPc/Gr and mPc/CNTs *** electrocatalytic behaviors of mPc/Gr and mPc/CNTs electrodes were further *** results show that the central rare earth metal has a large influence on the electrocatalytic *** the mPcs/Gr samples,ScPc with the smallest ionic radius and molecular size can be more uniformly dispersed in graphene,and the hydrogen precipitation overpotential of ScPc/Gr electrode is514 mV,corresponding to a Tafel slope of 148 mV/dec,with better electrocatalytic performance than other rare earth metal *** for the mPc/CNTs composites,LaPc,which has the largest ionic radius and molecular size,is more uniformly dispersed on the surface of CNTs,so that the LaPc/CNT electrode exhibits the best LSV performance with the smallest corresponding Tafel slope(176 mV/dec).The main reason is the different binding modes of mPcs molecules in Gr and *** rare earth phthalocyanine is combined with layered graphene,the smallest size of rare earth phthalocyanine(ScPc)is more easily embedded in the graphene layer,resulting in better homogeneity of the composite,larger effective contact area and better electrocatalytic *** contrast,when rare earth phthalocyanine is bound to carbon nanotubes in a tubular structure,it is mainly bound by attaching to the surface or being entangled by the carbon *** this case,the rare-earth phthalocyanine molecules(LaPc)with larger layer spacing can provide more contact area with CNTs,forming a more uniform and effective composite,which eventually provides more active sites and better electrocatalytic performance.

关键词： Electrocatalysis Rare earth phthalocyanines Graphene(Gr) Carbon nanotubes(CNTs) Composite

Auxiliary ball milling to prepare WS_(2)/graphene nanosheets composite for lithium-ion battery anode materials

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Tungsten 2024年第1期6卷 124-133页

作者： Yong-Lin Wu Jia-Bin Hong Wei-Xu Zhong Chun-Xiang Wang Zhi-Feng Li Sydorov dmytro Jiangxi Provincial Key Laboratory of Power Batteries and materials Jiangxi University of Science and TechnologyGanzhou 341000China Faculty of materials metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China Institute of Bioorganic Chemistry and Petrochemistry National Academy of Sciences of UkraineKiev 02160Ukraine

A novel nano-WS_(2)/graphene nanosheets(GNSs)composite is obtained by ball milling with xylitol as auxiliary agent and hightemperature *** improves the shear force during ball milling and well overcomes the van der Waals interactions between the interlayer of graphite and WS_(2).Through high-temperature calcination,GNSs and WS_(2) nanosheets can form tight interface *** produced WS_(2)/GNSs composites can be used as anode materials for lithium-ion batteries,while maintaining a high reversible specific capacity of 705 mAh·g^(-1)with the capacity retention of 95%at a current density of 250 mA·g^(-1)after 200 cycles,mainly because WS_(2)/GNSs composites have a higher Li^(+)diffusion coefficient of 2.2×10^(-9)cm^(2)·s^(-1)and a higher specific surface area of 70.10 m^(2)·g^(-1).As a result,the xylitol-assisted ball milling method designed in this work is suitable for extended preparation of peeling of two-dimensional layer materials into nanosheets.

关键词： Lithium-ion battery Anode material WS_(2) Graphene nanosheets Auxiliary ball milling

Element selection for functional materials discovery by integrated machine learning of elemental contributions to properties

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npj Computational materials 2023年第1期9卷 639-648页

作者： Andrij Vasylenko dmytro Antypov Vladimir V.Gusev michael W.Gaultois matthew S.Dyer matthew J.Rosseinsky Department of Chemistry University of LiverpoolCrown StreetLiverpool L697ZDUnited Kingdom Department of Computer Science University of LiverpoolAshton StreetLiverpool L693BXUnited Kingdom

The unique nature of constituent chemical elements gives rise to fundamental differences in *** materials based on their phase fields,defined as sets of constituent elements,before specific differences emerge due to composition and structure can reduce combinatorial complexity and accelerate screening,exploiting the distinction from composition-level *** and evaluation of novelty of materials classes align with the experimental challenge of identifying new areas of *** address this,we present PhaseSelect,an end-to-end machine learning model that combines representation,classification,regression and novelty ranking of phase *** leverages elemental characteristics derived from computational and experimental materials data and employs attention mechanisms to reflect the individual element contributions when evaluating functional performance of phase *** demonstrate this approach for high-temperature superconductivity,high-temperature magnetism,and targeted bandgap energy applications,showcasing its versatility and potential for accelerating materials exploration.

关键词： materials phase elements

The Convergence of 1-Periodic Branched Continued Fraction of the Special Form in Parabolic Regions

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Journal of mathematics and System Science 2014年第4期4卷 269-274页

作者： dmytro I. Bodnar mariia m. Bubniak st. Samchuk 32/6 Ternopi146002 Ukraine st. Kyivska 12/155 Ternopi146023 Ukraine

Branched continued fractions are one of the multidimensional generalization of the continued fractions. Branched continued fractions with not equivalent variables are an analog of the regular C-fractions for multiple power series. We consider 1-periodic branched continued fraction of the special form which is an analog fraction with not equivalent variables if the values of that variables are fixed. We establish an analog of the parabola theorem for that fraction and estimate truncation error bounds for that fractions at some restrictions. We also propose to use weight coefficients for obtaining different parabolic regions for the same fraction without any additional restriction for first element.

关键词： Continued fractions 1-periodic branched continued fraction of special form convergence uniform convergence truncation error bounds.

Fine equiaxed β grains and superior tensile property in Ti-6Al-4V alloy deposited by coaxial electron beam wire feeding additive manufacturing

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Acta metallurgica Sinica(English Letters) 2020年第10期33卷 1311-1320页

作者： Jiahua Zhang Yi Yang Sheng Cao Zhiqiang Cao dmytro Kovalchuk Songquan Wu Enquan Liang Xi Zhang Wei Chen Fan Wu Aijun Huang School of materials Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China School of materials University of ManchesterOxford RoadManchester M139PLUK JSC NVO Chervona Hvilya KievUkraine Shanghai Aircraft Design and Research Institute Shanghai 201210China Key Laboratory of Power Beam Processing AVIC Manufacturing Technology InstituteBeijing 100024China Department of materials Science and Engineering Monash UniversityClaytonVIC 3800Australia

Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.

关键词： Directed energy deposition Wire feeding additive manufacturing Ti–6Al–4V alloy Equiaxedβgrain Tensile properties

Catalytic performance of ternary mg-Al-Ce oxides for ethanol conversion into 1-butanol in a flow reactor

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燃料化学学报 2021年第3期49卷 346-357,I0001-I0010页

作者： Olga V.Larina Karina V.Valihura Pavlo I.Kyriienko Nina V.Vlasenko dmytro Yu.Balakin Ivan Khalakhan Katerina Veltruská Tomaz Cendak Sergiy O.Soloviev Svitlana m.Orlyk L.V.Pisarzhevsky Institute of Physical Chemistry of the National Academy of Sciences of Ukraine 31 Prosp.Nauky03028 KyivUkraine Institute of Physics of the National Academy of Sciences of Ukraine 46 Prosp.Nauky03028 KyivUkraine Charles University Faculty of Mathematics and PhysicsDepartment of Surface and Plasma ScienceV Holešovičkách 218000 PragueCzech Republic National Institute of Chemistry Department of Inorganic Chemistry and TechnologyHajdrihova 19SI-1001 LjubljanaSlovenia

An investigation of hydrotalcite-derived ternary mg-Al-Ce oxides as catalysts for vapour phase condensation of ethanol to 1-butanol in a flow reactor under atmospheric pressure was carried *** mg-Al-Ce oxide systems with mg/(Al+Ce)ratio from 1 to 4 were synthesized and characterized by XRD,SEm,NmR,and *** study of acid-base characteristics of the systems with different mg/(Al+Ce)ratio by NH3/CO_(2)quasi-equilibrium thermal desorption techniques shows that the ratio of the catalyst oxide components(mg,Al,Ce)can provide acid/base capacity ratio close to 3 for the effectivity of the target *** highest selectivity 68%is reached over mg-Al-Ce oxide catalyst with the ratio of mg/(Al+Ce)=2.

关键词： ethanol 1-butanol mg-Al-Ce hydrotalcite-derived oxides acid-base properties

40-meter-long REBCO tapes with critical current over 4,000 A/12 mm at 4.2 K and 13 T by advanced mOCVD

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Superconductivity 2024年第1期9卷 29-34页

作者： mahesh Paidpilli Chirag Goel Bhabesh Sarangi Siwei Chen Eduard Galstyan Jan Jaroszynski Griffin Bradford dmytro Abraimov Venkat Selvamanickam Department of mechanical Engineering Advanced Manufacturing InstituteTexas Center for SuperconductivityUniversity of HoustonHoustonTexasUSA AmPeers LLC HoustonTexasUSA National High magnetic Field Laboratory TallahasseeFloridaUSA

REBa_(2)Cu_(3)O_(7−δ)(REBCO,RE=rare earth)tapes doped with 5%and 15%Zr have been scaled up to lengths more than 40 m in a pilot‐scale advanced metal organic chemical vapor deposition(A‐mOCVD)*** precursor compositions used for the long tapes were guided by a study of the influence of(Ba+dopant)/Cu content on the critical current density(Jc)of 5 and 15 mol.%Hf‐and Zr‐added tapes at 4.2 K and 13 *** 40‐mlong tapes exhibited a critical current(Ic)over 4,000 A/12 mm at 4.2 K and 13 T as well as over 1,400 A/12 mm at 20 K and 20 *** critical current densities of a 40‐m‐long tape doped with 5%Zr at 4.2 K measured at the National High magnetic Field Laboratory(NHmFL)were>10 mAcm^(−2)and>5 mAcm^(−2)at 14 T and 30 T,respectively,which are over three times those of commercial REBCO *** infield Jc of 5%Zradded 40‐m‐long tapes was similar to those of previously‐reported high‐performance short samples made with 15%Zr or *** results demonstrate the excellent potential of A‐mOCVD for manufacturing high Ic REBCO tapes for use in ultrahigh‐field magnet applications.

关键词： High‐temperature superconductors mOCVD REBCO Critical current

Photoelectric Properties of Crystalline and Glassy PbGeS<sub>3</sub>

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Open Journal of Inorganic Non 2013年第3期3卷 29-36页

作者： dmytro Ivanovych Bletskan Vasyl mykolaiovych Kabatsii Uzhgorod National University Department of Physics Uzhgorod Ukraine Мucachevo State University Мucachevo Ukraine

The integrated investigations of the stationary characteristics of photoconductivity (the spectral distribution of photoconductivity (PC), luminous-ampere characteristics (LAC), temperature dependences of dark photoconductivity) and the thermostimulated current (TSC) for crystalline and glassy lead thiogermanate (PbGeS3) were performed. It was determined, as a function of crystals growing rate, there are one or two impurity maxima except for the native one in photoconductivity spectra. For the glassy lead thiogermanate in the range of wave lengths of 0.4 - 1.0 μm in PC spectra was revealed the hysteresis at the change of direction wave lengths sweep of incident light, conditioned by the phenomenon of induced impurity conductivity. The activation of PC, caused by thermal emptying of attachment levels, was observed on the temperature dependences of photoconductivity.

关键词： Semiconductors Chalcogenide Glasses Photoconductivity