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Glass-forming ability, phase formation and mechanical properties of glass-forming Cu-Hf-Zr alloys

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Progress in Natural Science:materials International 2019年第5期29卷 576-581页

作者： K.Kosiba Kaikai Song U.Kühn Gang Wang S.Pauly Leibniz ifw dresden Institute for Complex Materials School of Mechanical Electrical & Information Engineering Shandong University (Weihai) Laboratory for Microstructures Institute of Materials Shanghai University

The influence of Hf additions on the glass-forming ability（GFA）,phase formation and mechanical properties of Cu;Hf;Zr;（x=2,5,10,20 at.%）alloys has been systematically *** report on a distinct correlation between phase formation and GFA of Cu;Zr;-based *** additions of Hf reduce the thermal stability of the high-temperature B2Cu（Hf,Zr）phase,while the thermal stability of the corresponding undercooled melt is *** GFA of these alloy series gradually raises up to 10 at.%Hf,whereas at 20 at.%Hf,the GFA is drastically lowered,since the B2Cu（Hf,Zr）phase becomes unstable and the precipitation of the lowtemperature equilibrium phases is *** interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass *** composites not only show appreciable macroscopic plastic strain,but also high yield strength.

关键词： Metallic glasses Glass-forming ability Composites Continuous cooling transformation (CCT) diagram Mechanical properties

(RE)BaCuO/Ag Composites: The Role of Silver in Bulkmaterials and Joints

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Tsinghua Science and Technology 2003年第3期8卷 251-265页

作者： G.Krabbes P.Diko C.Wende Th.Hopfinger G.Fuchs ifw Leibniz-institute for Solid State and materials Research dresden D-01171 DresdenGermanyIFW Leibniz-Institute for Solid State and Materials Research DresdenD-01171 DresdenGermanyIFW Leibniz-Institute for Solid State and Materials Research DresdenD-01171 DresdenGermanyIFW Leibniz-Institute for Solid State and Materials Research DresdenD-01171 DresdenGermanyIFW Leibniz-Institute for Solid State and Materials Research DresdenD-01171 DresdenGermany

We have investigated the phase equilibria in (RE)BaCuO/Ag systems, the influence of Ag on the processing of (RE)BaCuO/Ag composites and the resulting properties. YBaCuO/Ag composites have been grown by the modified melt crystallization process with YBa2Cu3O7, Y2O3, Pt and Ag2O in the precursor. The improved strength of the YBaCuO/Ag composites compared with the conventional YBaCuO bulk material permitted us to magnetize these materials to achieve trapped fields up to 16 T (at 24 K) in the gap of a mini-magnet. The investigation of the microstructure revealed a remarkable increase of the spacing between micro-cracks especially of those perpendicular to a/b-planes when 12wt%Ag was added. In the case of SmBaCuO/Ag composites, Ag has a strong influence on processing and causes interactions between RE123 seeds and the sample. We show the growth of single-grain SmBaCuO/Ag composites in air and discuss the influence of post-annealing on increasing Tc and Jc. Furthermore, YBaCuO/Ag composites have been shown to be appropriate materials used as a solder to join large single grains to large arrays or to 'repair' grain boundaries in arrays grown by a multiseeding technique.

关键词： high-Tc superconductors bulk superconductors processing microstructure mechanical properties (RE)BaCuO/Ag composites

Layered barium vanadate nanobelts for high-performance aqueous zinc-ion batteries

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International Journal of Minerals,Metallurgy and materials 2021年第10期28卷 1684-1692页

作者： Xing-hua Qin Ye-hong Du Peng-chao Zhang Xin-yu Wang Qiong-qiong Lu Ai-kai Yang Jun-cai Sun institute of materials and Technology Dalian Maritime UniversityDalian 116026China institute for complex materials Leibniz Institute for Solid State and Materials Research(IFW Dresden e.V.HelmholtzstraBe 2001069 DresdenGermany materials Synthesis and Processing(IEK-1) Institute of Energy and Climate ResearchForschungszentrum Julich GmbH52425 JulichGermany

Aqueous zinc-ion batteries(ZIBs)are deemed as the idea option for large-scale energy storage systems owing to many alluring merits including low manufacture cost,environmental friendliness,and high operations ***,to develop high-performance cathode is still significant for practical application of ***,Ba_(0.23)V_(2)O_(5)·1.1H_(2)O(BaVO)nanobelts were fabricated as cathode materials of ZIBs by a typical hydrothermal synthesis *** from the increased interlayer distance of 1.31 nm by Ba2+ and H2O pre-intercalated,the obtained BaVO nanobelts showed an excellent initial discharge capacity of 378 mAh·g^(-1) at 0.1 A·g^(-1),a great rate performance(e.g.,172 mAh·g^(-1) at 5 A·g^(-1)),and a superior capacity retention(93% after 2000 cycles at 5 A·g^(-1)).

关键词： aqueous zinc-ion batteries barium vanadate nanobelts increased interlayer distance long cycle life

Synergistic protection of Si anode based on multi-dimensional graphitic carbon skeletons

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Nano Research 2022年第9期15卷 8146-8155页

作者： Qitao Shi Haiming Wang Junhua Zhou HuyQuang Ta Jiaqi Wang Xueyu Lian Klaudia Kurtyka Barbara Trzebicka Thomas Gemming Mark H.Rümmeli Soochow institute for Energy and materials Innovation College of EnergyKey Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou 215006China institute for complex materials IFW Dresden20 Helmholtz StrasseDresden 01069Germany Centre of Polymer and Carbon materials Polish Academy of SciencesM.Curie-Sklodowskiej 34Zabrze 41-819Poland Thomas Gemming-institute of Environmental Technology VSB-Technical University of Ostrava17.Listopadu 15Ostrava 70833Czech Republic

Inspired by the natural corn structure,a Si@hollow graphene shell@graphene(Si@GS@G)anode material was prepared in which silicon nanoparticles were preliminarily anchored onto the surface of an elastic graphene shell and further constrained using graphene *** graphene oxide shells with abundant surficial hydrogen bonds,which were synthesized using a novel bottom-up method,were used as an intermediate material to anchor positively charged silicon nanoparticles via electrostatic attraction and achieve a rational spatial *** inner hollow graphene shell anchorage and outer graphene constraint synergistically constituted a porous and robust conductive corn-like *** as-fabricated Si@GS@G anode afforded efficient electron and ion transport pathways and improved structural stability,thereby enhancing Li+storage capability(505 mAh·g^(−1)at 10 A·g^(−1))and extending the lifespan compared to the single hollow graphene shell or graphene sheet-protected Si anode(72%capacity retention after 500 cycles).The improved kinetics of the Si@GS@G anode were investigated using electro impedance spectroscopy,galvanostatic intermittent titration,and pseudocapacitance contribution rate analysis,and the structural evolution was analyzed using ex situ electron *** study proposes a novel hollow graphene oxide shell as an activated intermediate material for designing a porous electrode structure that facilitates an enhanced electrochemical performance.

关键词： synergistic protection multi-dimensional graphitic carbons corn-like structure elastic skeleton Si/C anode

Micro-mechanical deformation behavior of CoCrFeMnNi high-entropy alloy

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Journal of materials Science & Technology 2022年第5期100卷 237-245页

作者： Kaiju Lu Ankur Chauhan Dimitri Litvinov Aditya Srinivasan Tirunilai Jens Freudenberger Alexander Kauffmann Martin Heilmaier Jarir Aktaa institute for Applied materials Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtz-Platz 176344 Eggenstein LeopoldshafenGermany institute for Applied materials Karlsruhe Institute of Technology(KIT)Engelbert-Arnold-Strasse 476131 KarlsruheGermany Leibniz institute for Solid State and materials Research dresden(ifw dresden) Helmholtzstr.20D-01069 DresdenGermany institute of materials Science Technische Universität Bergakademie FreibergGustav-Zeuner-Str.509599 FreibergGermany

In the present study,the micro-mechanical behavior of Co CrFeMnNi high-entropy alloy was investigated using an in-house micro-tensile setup at room temperature and 550℃ at different strain *** properties are compared with those obtained using a commercial macro-tensile setup to check a potential sample size *** show that mechanical properties such as yield strength,ultimate tensile strength and uniform elongation are independent of the sample ***,the total elongation-to-failure of micro-samples is found to be lower than those of *** from this,the material exhibits serrated plastic flow,which is strain rate dependent in terms of the onset strain and shape of serrations at 550℃.Furthermore,transmission electron microscopy investigations were performed to correlate the occurrence of serrations to the observed distinct dislocation *** results provide direct evidence that dislocations are curved and hence effectively pinned and unpinned at the lowest applied strain rate,which might be responsible for the occurrence of serrated plastic flow.

关键词： High-entropy alloy Mechanical properties Micro-tensile Deformation mechanism Serration

Effect of Powder Particle Shape on the Properties of In Situ Ti–TiB Composite materials Produced by Selective Laser Melting

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Journal of materials Science & Technology 2015年第10期31卷 1001-1005页

作者： Hooyar Attar Konda G.Prashanth Lai-Chang Zhang Mariana Calin Ilya V.Okulov Sergio Scudino Chao Yang Jürgen Eckert School of Engineering Edith Cowan University ifw dresden Institute for Complex Materials TU dresden Institute of Materials Science National Engineering Research Center of Near-Net-Shape Forming for Metallic materials South China University of Technology

This work studied the preparation of starting powder mixture influenced by milling time and its effect on the particle morphology （especially the shape） and, consequently, density and compression properties of in situ Ti-TiB composite materials produced by selective laser melting （SLM） technology. Starting powder composite system was prepared by mixing 95 wt% commercially pure titanium （CP-Ti） and 5 wt% titanium diboride （TiB2） powders and subsequently milled for two different times （i.e. 2 h and 4 h）. The milled powder mixtures after 2 h and 4 h show nearly spherical and irregular shape, respectively. Subsequently, the resultant Ti-5 wt% TiB2 powder mixtures were used for SLM processing. Scanning electron microscopy image of the SLM-processed Ti-TiB composite samples show needle-shape TiB phase distributed across the Ti matrix, which is the product of an in-situ chemical reaction between Ti and TiB2 during SLM. The Ti-TiB composite samples prepared from 2 h and 4 h milled Ti-TiB2 powders show different relative densities of 99.5% and 95.1%, respectively. Also, the compression properties such as ultimate strength and compression strain for the 99.5% dense composite samples is 1421 MPa and 17.8%, respectively, which are superior to those （883 MPa and 5.5%, respectively） for the 95.1% dense sample. The results indicate that once Ti and TiB2 powders are connected firmly to each other and powder mixture of nearly spherical shape is obtained, there is no additional benefit in increasing the milling time and, instead, it has a negative effect on the density （i.e. increasing porosity level） of the Ti-TiB composite materials and their mechanical properties.

关键词： Selective laser melting In situ Ti-TiB composite Powder shape Density Mechanical properties

Mechanical behavior and deformation mechanism of shape memory bulk metallic glass composites synthesized by powder metallurgy

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Journal of materials Science & Technology 2022年第19期114卷 42-54页

作者： Tianbing He Tiwen Lu Daniel Sopu Xiaoliang Han Haizhou Lu Kornelius Nielsch Jürgen Eckert Nevaf Ciftci Volker Uhlenwinkel Konrad Kosiba Sergio Scudino Leibniz ifw dresden Institute for Complex MaterialsHelmholtzstraße 2001069 DresdenGermany Guangdong Key Laboratory for Advanced Metallic materials Processing South China University of TechnologyGuangzhou 510640China Erich Schmid institute of materials Science Austrian Academy of SciencesJahnstraße 12Leoben A-8700Austria Leibniz ifw dresden Institute for Metallic MaterialsHelmholtzstraße 2001069 DresdenGermany TU dresden Institute of Materials Science01062 DresdenGermany TU dresden Institute of Applied Physics01062 DresdenGermany Department materials Physics Montanuniversität LeobenJahnstraße 12A-8700 LeobenAustria Leibniz institute for materials Engineering IWT 28359 BremenGermany University of Bremen Faculty of Production Engineering28359 BremenGermany

The synthesis of martensitic or shape-memory bulk metallic glass composites(BMGCs)via solidification of the glass-forming melts requires the meticulous selection of the chemical composition and the proper choice of the processing parameters in order to ensure that the glassy matrix coexists with the desired amount of austenitic ***,a relatively limited number of such systems,where austenite and glassy matrix coexist over a wide range of compositions,is ***,we study the effective-ness of powder metallurgy as an alternative to solidification for the synthesis of shape memory ***_(48)Cu_(36)Al_(8)Ag_(8)matrix composites with different volume fractions of Ni_(50.6)Ti_(49.4)are fabricated using hot pressing and their microstructure,mechanical properties and deformation mechanism are investigated employing experiments and *** results demonstrate that shape-memory BMGCs with tun-able microstructures and properties can be synthesized by hot *** phase stability of the glass and austenitic components across a wide range of compositions allows us to examine fundamental as-pects in the field of shape memory BMGCs,including the effect of the confining stress on the martensitic transformation exerted by the glassy matrix,the contribution of each phase to the plasticity and the mechanism responsible for shear band *** present method gives a virtually infinite choice among the possible combinations of glassy matrices and shape memory phases,expanding the range of accessible shape memory BMGCs to systems where the glassy and austenitic phases do not form simul-taneously using the solidification route.

关键词： Metallic glass composites Niti alloys Mechanical properties Shear bands Martensitic transformation

Plastic deformation of a Zr-based bulk metallic glass fabricated by selective laser melting

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Journal of materials Science & Technology 2021年第1期60卷 139-146页

作者： L.Deng K.Kosiba R.Limbach L.Wondraczek U.Kühn S.Pauly ifw dresden Institute for Complex MaterialsHelmholtzstraße 20D-01069DresdenGermany Otto Schott institute of materials Research University of JenaFraunhoferstraße 6D-07743JenaGermany University of Applied Sciences Aschaffenburg Würzburger Straße 45D-63743AschaffenburgGermany

Fully amorphous Zr_(52.5)Cu_(17.9)Ni_(14.6)Al_(10)Ti_(5) bulk metallic glass(BMG) samples with a relative density exceeding 98% were fabricated via selective laser melting(SLM).High fracture stresses of around1700 MPa and a reproducible plastic strain of about 0.5% were obtained for cylindrical SLM *** analysis of the observed serrations during compressive loading implies that the shear-band dynamics in the additively manufactured samples distinctly differ from those of the as-cast *** phenomenon appears to originate from the presence of uniformly dispersed spherical pores as well as from the more pronounced heterogeneity of the glass itself as revealed by instrumented *** these heterogeneities,the shear bands are straight and form in the plane of maximum shear *** manufacturing,hence,might not only allow for producing large BMG samples with complex geometries but also for manipulating their deformation behaviour through tailoring porosity and structural heterogeneity.

关键词： Powder bed fusion Selective laser melting Bulk metallic glass Serrated flow Heterogeneity

Nanoscale chemical segregation to twin interfaces in τ-MnAl-C and resulting effects on the magnetic properties

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Journal of materials Science & Technology 2023年第3期134卷 22-32页

作者： Panpan Zhao Markus Gusenbauer Harald Oezelt Daniel Wolf Thomas Gemming Thomas Schrefl Kornelius Nielsch Thomas George Woodcock Leibniz ifw dresden Helmholtzstr.20Dresden 01069Germany TU dresden Institute of Materials ScienceDresden 01062Germany Department for Integrated Sensor Systems Danube University KremsKrems an der Donau 3500Austria

In this study,aberration-corrected scanning transmission electron microscopy coupled with electron energy-loss spectroscopy(STEM-EELS)was used to investigate the atomistic structure and chemical com-position of true twin and order twin boundaries in ferromagneticτ-*** twins and order twins were distinguished based on the diffraction patterns using *** elemental segregation was observed at the coherent true twin boundary but some Mn enrichment within a region of about 1.5-2 nm was found at the incoherent true twin boundary.A transition region with Mn enrichment about 4-6 nm wide was found at the order twin boundary.A carbon cluster with a size of around 5 nm was also found at the twin *** simulations were conducted to study the effect of this chemical seg-regation at twin interfaces on the magnetic *** results showed that the coercivity tends to increase with increasing structural and chemical disorder at the interface.

关键词： τ-MnAl-C Twin boundaries Elemental segregation STEM-EELS Micromagnetic simulations