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Electrical and mechanical properties of (Bi, Pb)-2223 substituted by holmium

Journal of Advanced Ceramics 2016年第1期5卷 54-69页

作者： W.ABDEEN S.MARAHBA R.AWAD A.I.ABOU ALY I.H.IBRAHIM M.MATAR superconductivity and metallic glass lab Physics Department Faculty of ScienceAlexandria University Alexandria EgyptPhysics Department University College at Al-Gamom Umm Al-Qura University Saudi Arabia Physics Department Faculty of Science Beirut Arab University(BA U) Beirut Lebanon superconductivity and metallic glass lab Physics Department Faculty of ScienceAlexandria University Alexandria Egypt

The effect of the partial substitution of Ca2+ by Ho3+ ions on the electrical and mechanical properties of the superconducting phase (Bi,Pb)-2223 was studied. Superconducting samples of the type (Bi1.8Pb0.4)Sr2Ca2.1?x Ho xCu3.1O10+δ were prepared by solid-state reaction technique under ambient pressure, and characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The superconducting transition temperature T c and pseudogap temperature T* were estimated from electrical resistivity measurements, while the critical current density J c was determined from I-V curves. The electrical resistivity data were discussed according to bipolaron model in the absence of thermally excited individual polarons. The sample with x = 0.025 showed the highest phase volume fraction, T c, and J c. Room temperature Vickers microhardness measurements were carried out at different applied loads (0.25-5 N) in order to investigate the performance of the mechanical properties of (Bi1.8Pb0.4)Sr2Ca2.1?x Ho xCu3.1O10+δ phase. It was found that all the samples exhibit normal indentation size effect (ISE). The Vickers microhardness number H V increased as x increased from 0 to 0.025. The experimental results were discussed in view of Meyer’s law, Hays-Kendall (HK) approach, elastic/plastic deformation (EPD) model, and proportional specimen resistance (PSR) model. The load independent (true) microhardness of (Bi1.8Pb0.4)Sr2Ca2.1?x Ho xCu3.1O10+δ superconducting samples showed identical behavior to that of the PSR model.

关键词： (Bi,Pb)-2223 phase Ho substitution Vickers microhardness bipolaron model pesudogap temperature

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Structural transformation and rheological processes in bulk metallic glass Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5)

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中国有色金属学会会刊：英文版 2004年第2期14卷 218-222页

作者：王敬丰蒲健邹辉甘章华柳林肖建中 State Key lab of Die and Mould Technology

The temperature dependence of strain and strain rate of the Zr41Ti14Cu12.5Ni10Be22.5（Vit1） bulk metallic glass （BMG） under constant heating condition was derived from the static extension method with a dynamic thermal mechanical analyzer （DMA）. A few strain rate peaks, which corresponds to the glass transition and multistep crystallization in the differential scanning calorimeter （DSC） examination, were observed in the curves of the relation between strain rate and temperature. The onset of viscous flow and the end of glass transition are interrelated, the first and second strain rate peaks correspond with the first and second crystallization transition processes, respectively. The influence of stress on strain and strain rate was researched. It is found that the rheological behaviour of BMG Vit1 changes from elasticity to anelasticity, finally to the Newtonian viscous flow along with increasing temperature.

关键词： Zr41Ti14Cu12.5 锆合金大块金属玻璃流变学结构转变 BMG DMA DSC

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Effect of energy density on defect evolution in 3D printed Zr-based metallic glasses by selective laser melting

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Science China(Physics,Mechanics & Astronomy) 2020年第2期63卷 104-110页

作者： Wei Xing Di Ouyang Zhen Chen Lin Liu School of Materials Science and Engineering and State Key Lab for Materials Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China State Key lab for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China

In this study, the defects in 3D printed Zr-based bulk metallic glasses(BMGs) fabricated by selective laser melting(SLM) under different energy densities have been investigated via both experimental and simulation approaches. Different defects, including balling, interlayer pores, open pores and metallurgical pores, are detected in the 3D-printed Zr-based MGs depending on the energy inputs. Balling mainly occurs at a relatively low energy density(E<8.33 J/mm^3) due to the incomplete melting of particles, while interlayer pores and open pores are formed at modest energy densities(E=13.89-16.67 J/mm^3) because of incomplete welding and insufficient filling of molten liquid between layers. Fine metallurgical pores appear on the upper surface at relatively high energy densities(E=20.83-27.78 J/mm^3), which originate from gas escaping from molten pools during rapid solidification of the melt. Computational fluid dynamics(CFD) simulations are carried out to verify the experimental observations. The CFD simulations reveal that the various defects formed in the 3D-printed Zr-based BMG are related to the melt flow behaviours in the molten pools under different energy densities. The present work provides in-depth understandings of defect formation in the SLM process and provides methods for eliminating these defects in order to enhance the mechanical performance of 3D printed BMGs.

关键词： metallic glass selective laser melting defect formation mesoscopic simulation

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An Attempt to Prepare metallic glasses from Quasicrystals

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Chinese Physics Letters 2016年第4期33卷 93-95页

作者：李子敬赵林然王玉婷陈泽明涂文康张亚齐薄宏刘迎丹王利民 State Key lab of Metastable Materials Science and Technology and College of Materials Science and EngineeringYanshan University

Icosahedrons in supercooled liquids and glasses are considered to be of significance for the glass formation in alloy systems. Starting from the similarity of the local structure of quasicrystals to the icosahedrons in metallic glasses, a scheme is put forward to prepare metallic glasses based on a well-known quasicrystal Zr40Ti40Ni20. A series of （Zr4o Ti40Ni20 ）lOO-x Cos metallic glasses are fabricated, and the optimized glass forming composition is determined at （Zr40 Ti40Ni20 ）92 Cos. The results show that the glass-forming ability of the alloys is c10sely related to the quasicrystalline phases. The mechanism of the enhanced glass-forming ability is discussed.

关键词： Ti Ni Zr of An Attempt to Prepare metallic glasses from Quasicrystals from

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Thermodynamic model for glass forming ability of ternary metallic glass systems

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中国有色金属学会会刊：英文版 2001年第5期11卷 684-690页

作者：惠希东陈国良边赞何国王晓民 Univ Sci & Technol Beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

The thermodynamic model of multicomponent chemical short range order (MCSRO) was established in order to evaluate the glass forming ability (GFA) of ternary alloys. Comprehensive numerical calculations using MSCRO software were conducted to obtain the composition dependence of the MCSRO undercooling in Zr Ni Cu, Zr Si Cu and Pd Si Cu ternary systems. By the MCSRO undercooling principle, the composition range of Zr Ni Cu system with optimum GFA is determined to be 62.5 ～ 75 Zr, 5～ 20 Cu, 12.5 ～ 25 Ni ( n (Ni)/ n (Cu)=1～5). The TTT curves of Zr Ni Cu system were also calculated based on the MCSRO model. The critical cooling rates for Zr based alloy with deep MSCRO undercooling are estimated to be as low as 100?K/s, which is consistent with the practical cooling rate in the preparation of Zr based bulk metallic glass (BMG). The calculation also illustrates that the easy glass forming systems such as Pd based alloys exhibit an extraordinary deep MCSRO undercooling. It is shown that the thermodynamic model of MCSRO provides an effective method for the alloy designing of BMG.

关键词： thermodynamic model multicomponent chemical short range order (MCSRO) undercooling bulk metallic glasses (BMG) glass forming ability (GFA), Zr Ni Cu system

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Annealing Embrittlement in Fe-Mo-Si-B Amorphous Alloy

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Journal of Materials Science & Technology 1997年第1期13卷 61-64页

作者： Li, JM Quan, MX Hu, ZQ National Key lab. of RSA Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

Annealing at T-a=200 degrees C or so, the enhancement in the average tensile fracture strength of as-quenched (Fe0.99Mo0.01)(78)Si9B13 metallic glass increases about 7 similar to 8%. The origin of the annealing embrittlement at 244 degrees C in the metallic glass (Fe0.99Mo0.01)(78)Si9B13 was revealed that due to the formation of nanoscale granular with bcc structure resulting in the stress localization. The temperature of annealing embrittlement was in agreement with the calculated value from T-bcc=0.637 T-c (T-c is the crystallized temperature), based on micromechanism of crystallization of metallic glass.

关键词： metallic glass

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Locating Malleable Bulk metallic glasses in Zr-Ti-Cu-Al Alloys with Calorimetric glass Transition Temperature as an Indicator

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Journal of Materials Science & Technology 2012年第12期28卷 1109-1122页

作者： Qiang He Jian Xu jianxu@*** Chinese Acad Sci Shenyang Natl Lab Mat Sci Inst Met Res Shenyang 110016 Peoples R China

We defined the plastic deformability under constrained loading conditions as malleability for bulk metallic glass （BMG） materials. Quaternary Zr-Ti-Cu-Al alloys in the Zr-rich composition range are selected to investigate the compositional dependence of malleability assessed by bending testing and glass transition temperature （Tg ）. As indicated, increasing the Al or Cu concentration in the alloys leads to the rise of T g . The Zr（61）Ti2Cu（25）Al（12）（ZT1） and Zr（61.6）Ti（4.4）Cu（24）Al（10）（ZT3） alloys exhibit an optimal combination of lower T g and higher glass-forming ability. The malleable BMGs such as ZT1 manifests two characters during deformation, the stable propagation of a single shear band indicated by large shear offsets and easy proliferation of shear bands. With increasing the T g of BMG, the yield strength σy,Young＇s modulus and shear modulus simultaneously increase as well, while the Poisson s ratio decreases. The σy of ZT1 BMG is about 1680 MPa in compression and 1600 MPa in tension. In tensile loading, no any visible plasticity appears even when the strain rate increases up to the order of magnitude of 10（-1）s（-1）. In consistent with the T g , malleability of Zr-Ti-Cu-Al BMGs manifests significant compositional dependence. The malleable BMG is associated with lower Tg , as well as lower shear modulus or higher Poisson s ratio, which can be understood on the basis of the correlation of Tg with shear energy barrier in metallic glass. Thus, the calorimetric Tg can be used as an indicator to screen malleable BMG-forming composition, with advantage of experimental accessibility.

关键词： metallic glass glass transition Malleability Bending Elastic constants

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Formation and crystallization of bulk Pd_(82)Si_(18) amorphous alloys

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中国有色金属学会会刊：英文版 2003年第5期13卷 1056-1061页

作者：蒲建王敬丰肖建中崔昆 State Key lab of Plastic forming Simulation and Die & Mould Technology Huazhong University of Science & Technology Wuhan 430074China

Bulk amorphous Pd 82 Si 18 alloy with the largest diameter of 8 mm was prepared by water quenching the molten alloy with flux medium in a quartz tube. The calculation result indicates that the bulk Pd 82 Si 18 amorphous alloys have a low critical cooling rate ( R c) of 4.589 K/s or less. The experimental results show that purifying melt may improve glass forming ability(GFA) of undercooled melt, while liquid phase separation (LPS) of undercooled melt will decrease its GFA. There are some differences in crystallization experiments between bulk metallic glass and amorphous ribbons of Pd 82 Si 18 alloys. These include the numbers of exothermic peak, glass transition temperature T g, crystallization temperature T x, region of undercooling liquid (Δ T=T x- T g) respectively. The links of cooling rates of melt and crystallization of Pd 82 Si 18 amorphous alloys are explored.

关键词：大块非晶合金铅硅合金过冷临界冷却速率玻璃态形成

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Micromechanism of Crystallization in Multicomponent metallic glass

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Journal of Materials Science & Technology 1996年第6期12卷 401-408页

作者： Jianmin LP Mingxiu QUAN and Zbuangqi HU (National Key lab. of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China)(To whom correspondence should be addressed) National Key lab. of RSA Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

A micromechanism in an atomic level of crystallization of transition metal-metalloid TM(80)M(20) metallic glass is thermodynamically proposed by taking Bernal polyhedra as the starting structure of metallic glass. It is composed of two competitively processes: (i) densification process of atom cluster leads to the formation of the precursor in amorphous matrix; (ii) the growth of atom cluster leads to the decreasing packing density. The preferential precipitation sequence of metastable phase is bcc, bet, cpc (close-packed crystal, hcp or fee structure). A metastable phase decomposition (Fe,Mo)(23)B-6 (fcc)-Fe2B highly strained bet phase was observed during crystallization of (Fe(0.99)M(0.01))(78)Si9B13 metallic glass, which is related to the occurrence of nanocrystalline.

关键词： Si Mo Rev Micromechanism of Crystallization in Multicomponent metallic glass Nature

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Characterization,Removal and Evaluation of Oxide Film in the Diffusion Bonding of Zr_(55)Cu_(30)Ni_5Al_(10) Bulk metallic glass

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Journal of Materials Science & Technology 2014年第7期30卷 722-730页

作者： Haiyan Chen Jian Cao Xiaoguo Song Jiakun Liu Jicai Feng State Key lab of Advanced Welding and Joining Harbin Institute of Technology School of Materials Science and Engineering Harbin Institute of Technology at Weihai

The composition of oxide film of ZrssCu3oNi5Al10 bulk metallic glass was identified by X-ray photoelectron spectroscopy. In addition, the relatively sound joints of bulk metallic glass without macroscopic deformation were obtained by removing the oxide film before diffusion bonding. The joint interfaces were observed by scanning electron microscopy and atomic force microscopy. The hardness of joints near the interface was higher than that far away from the interface, which is attributed to the difference of structural relaxation. According to the result of micro-focused X-ray diffractometry and transmission electron microscopy, the joints retained the amorphous structure when the holding time is less than 20 min. The surface area fraction of oxide film on the interface of joints was detected by ultrasonic inspection. Moreover, the surface area fraction of oxide film is in excellent agreement with the theoretical value calculated by shear strength. The result indicated that surface oxide film is the dominant barrier on the diffusion bonding of bulk metallic glass rather than low atomic diffusion coefficient.

关键词： Bulk metallie glass Diffusion Surface Diffusion bonding Oxide film

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