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A Diagram for Glass Transition and Plastic Deformation in Model Metallic Glasses

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Journal of Materials Science & Technology 2014年第6期30卷 546-550页

作者： X.Q.Gao w.h.wang h.Y.Bai Institute of Physics Chinese Academy of Sciences

In this paper, we report a strain rate related glass transition in model SrCaYbMg（Li）Zn（Cu） metallic glasses at room temperature. A critical strain rate, equivalent to glass transition temperature, is found for the strain rate induced glassy state to liquid-like viscoplastic state translation. The results show that the observation time, equivalent to temperature and stress, is a key parameter for the transition between the glass and supercooled liquid states. A three-dimension glass transition diagram involved in time, temperature and stress in metallic glasses is established.

关键词： homogeneous plastic flow Glass transition Metallic glass

Microstructural evolution and superelastic properties of ultrafine-graine d NiTi-base d shape memory alloy via sintering of amorphous ribbon precursor

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Journal of Materials Science & Technology 2023年第7期138卷 80-92页

作者： w.S.Cai h.Z.Lu h.Z.Li Z.Liu h.B.Ke w.h.wang C.Yang National Engineering Research Center of Near-net-shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China

NiTi-based shape memory alloys(SMAs)are considered as cutting-edge intelligent functional ***,it remains a great challenge to obtain ultrafine-grained(UFGed)bulk materials with mm-scale size as well as outstanding superelastic ***,UFGed bulk Ti_(35)Zr_(15)Ni_(35)Cu_(15)NiTi-based SMA is successfully prepared via spark plasma sintering of amorphous ribbon precursor at different sintering temperatures,and microstructural evolution and superelastic properties are symmetrically *** is found that its grain size ranges from UFG to micro-grain with increased sintering temperature regard-less of the predominant B2 matrix in all bulk ***,the orientation relationships between B2 matrix and nano-scale fcc(Ti,Zr)_(2)Ni precipitate evolve from coherent to ***,the UFGed samples exhibit perfect superelasticity with the high recoverable strain of∼5.8%,the stable recov-ery rate above 99%,and the great critical stress inducing martensitic transformation higher than 1 GPa,far superior to the corresponding ones of suction-cast micro-grained TiZrNiCu ***,the perfect superelasticity is attributed to the good resistance to dislocation slip or grain boundary slip by residual nano-scale amorphous phase or secondary phase of coherent and semi-coherent fcc(Ti,Zr)_(2)Ni *** addition,the gentle superelastic plateau is associated to the favorable transfer stress and the strong ability to accommodate dislocation movement,which is generated by the coherent interface between nano-scale fcc(Ti,Zr)_(2)Ni and UFGed B2 *** results suggest that spark plasma sintering of amorphous alloy precursor is a feasible route to obtaining excellent superelasticity in NiTi-based SMAs.

关键词： Shape memory alloy Amorphous alloy Microstructure Superelasticity

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Foreword

Journal of Materials Science & Technology 2014年第6期30卷 I0001-I0002页

作者： w.h.wang Z.F.Zhang Institute of Physics Chinese Academy of Sciences at Beijing

As a new class of advanced materials, metallic glasses （also often referred as amorphous alloys） possess a combination of unique amorphous structure and remarkably impressive mechanical and physical properties, and are now at the cutting edge of research. The emergence of bulk metallic glasses （BMGs） provides more alloy compositions, large geometric size and diverse mechanical behaviors for some fundamental issues such as deformation and fracture mechanisms of glassy materials and potentiates possibly great applications. In particular, the BMG-s exhibit many unique mechanical properties, such as superior strength and hardness, excellent scratch and wear resistance, extremely high elastic limit, and diverse fracture toughness （varying significantly from approaching ideal brittleness like the oxide glasses for Mg-based BMGs to the highest known damage tolerance for Pd-based BMGs） and patterns （such as dimple structures, nanoscale periodic corrugations, and fiver patterns）. It has become possible to experimentally characterize the mechanical behaviors of metallic glasses and to explore their correlations with the processing conditions, structures and other properties, and accordingly in a more general sense, to understand the deformation, energy dissipation, and fracture mechanisms in the disordered glassy materials. The important and interesting mechanical properties and deformation mechanisms are currently the focus of intense research in the material science community, and the corresponding studies on them are progressing at a fast pace.

关键词： BMGs Foreword

Composition and size dependent torsion fracture of metallic glasses

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Journal of Materials Science & Technology 2021年第23期82卷 153-160页

作者： J.Dong J.Shen Y.h.Sun h.B.Ke B.A.Sun w.h.wang h.Y.Bai Institute of Physics Chinese Academy of SciencesBeijing100190PR China College of Materials Science and Opto Electronic Technology University of Chinese Academy of SciencesBeijing100049PR China Songshan Lake Materials Laboratory DongguanGuangdong523808PR China

The fracture of metallic glasses(MGs)of different compositions and sizes down to micrometers under torsion loading were systematically *** to the flat shear fracture along the circumferential plane as commonly supposed under torsion,we find that the torsion fracture of metallic glasses can deviate from flat shear plane,and the fracture angle is closely dependent on the composition and the size of MG *** a conversion method,we show that the torsion fracture of both millimeterand micrometer-sized MGs can be described by the ellipse fracture criterion as originally proposed for the tension *** deviation from the circumferential shear plane under torsion is further shown to intrinsically relate to the fracture toughness of *** tougher MG tends to have a smaller fracture angle with respect to the maximum shear plane,and vice versa,indicating a correlation between the fracture toughness and pressure/normal stress sensitivity in *** results provide new insights on the fracture mechanism and are helpful to design and control the deformation and fracture behavior of MGs under torsion loading.

关键词： Metallic glasses Torsion fracture Pressure sensitivity Fracture toughness

Effect of solute atom concentration and precipitates on serrated flow in Mg-3Nd-Zn alloy

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Journal of Materials Science & Technology 2018年第7期34卷 1236-1242页

作者： w.h.wang D.wu R.S.Chen X.N.Zhang State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University The Group of Magnesium Alloys and Their Applications Institute of Metal Research Chinese Academy of Sciences

Influence of solute atom concentration and precipitates on serrated flow, i.e., Portevin-Le Chatelier effect, was studied in Mg-3Nd-Zn alloy by tensile test at 250℃ with a strain rate of l x 10^-3 s^-1 Microstructure and tensile property of the Mg-3Nd-Zn alloy in solution and aging conditions were also investigated. Results indicate that the serrated flow was weakened with aging time, and geometry of the serrations changed from sharp to rounded corner. Through analyzing the mechanism of the interactions between dislocations and solute atoms, it was identified that the precipitates did not only weaken the serrated flow due to the decrease in the concentration of solute atom, but also regulate the serration type by restraining the movement of dislocations during high temperature deformation.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

关键词： Magnesium alloy Serrated flow Precipitate heat treatment Deformation behavior

Materials Futures—an open access journal to serve the materials science community

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Materials Futures 2022年第1期1卷 1-2页

作者： J K Zhao w h wang T Brezesinski Songshan Lake Materials Laboratory Dongguan 523808GuangdongChina Institute of Physics Chinese Academy of SciencesBeijing 100190China Institute of Nanotechnology Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtz-Platz 1Eggenstein-Leopoldshafen 76344Germany

Materials Futures is co-published by the Songshan Lake Materials Laboratory and the UK’s IOP Publishing house,with support from the Institute of Physics,Chinese Academy of *** journal is dedicated to publishing seminal works in wide-ranging areas including metals and ceramics,energy materials,nanomaterials,quantum materials and *** scope covers studies regarding novel materials,materials properties and applications,as well as materials computation,theory and design(synthesis,processing,characterization etc).It strives to serve the research community and aims to become a top-tier journal for materials science.

关键词： journal Futures ceramics

hardening and toughening effects of intermediate nanosized structures in a confined amorphous alloy film

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Journal of Materials Science & Technology 2022年第23期118卷 44-53页

作者： Z.Q.Chen M.C.Li X.Tong Y.Zhao J.Y.Xie S.w.Guo P.huang F.wang h.B.Ke B.A.Sun w.h.wang Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China Xinjiang Key Laboratory of Solid State Physics and Devices and School of Physical Science and Technology Xinjiang UniversityXinjiangUrumqi 830046China Key Laboratory of LCR Materials and Devices of Yunnan Province School of Materials and EnergyYunnan UniversityKunming 650091China State-Key Laboratory for Mechanical Behavior of Material Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong UniversityXi’an 710049China National Demonstration Center for Experimental Mechanics Education Xi’an Jiaotong UniversityXi’an 710049China

The plastic deformation of amorphous alloys is well known to be localized into shear bands(SBs),which are believed to stem from the atomic-scale flow defects,i.e.,shear transformation zones(STZs).Yet,the bridge between the mesoscopic SBs and the atomic-scale STZs remains poorly *** this work,through thermally activating pronouncedβrelaxations in the well-designed crystalline-layer confined amorphous(CLCA)Ni w alloy films,we experimentally captured and observed an intermediate nanosized structure termed as“nano shear bands”(NSBs)with a typical size of 1–2 nm in thickness and5–10 nm in *** influences of such NSB structures on the macroscale deformation behavior were systematically *** was found that NSBs lead to both hardening and toughening effects for the CLCA films,as they promote multiple and controlled shear banding deformation,which results in enhanced *** intermediate NSB structure could connect the microstructural characteristics and macroscopic plasticity in amorphous alloys and may provide new insights for understanding the microscopic deformation mechanism of amorphous alloys as well as tuning/designing their properties.

关键词： Amorphous alloys Nano shear band hardening Toughening Crystallization

Interface dominated deformation transition from inhomogeneous to apparent homogeneous mode in amorphous/amorphous nanolaminates

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Journal of Materials Science & Technology 2022年第4期99卷 178-183页

作者： Z.Q.Chen M.C.Li J.S.Cao F.C.Li S.w.Guo B.A.Sun h.B.Ke w.h.wang Songshan Lake Materials Laboratory Dongguan 523808PR China Institute of Physics Chinese Academy of SciencesBeijing 100190PR China Institute of Materials Engineering Nanjing UniversityNantong 226019PR China School of Physics Science and Technology Xinjiang UniversityXinjiang 830046PR China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049PR China State Key Laboratory for Mechanical Behavior of Material Xi'an Jiaotong UniversityXi’an 710049PR China

The amorphous/amorphous nanolaminates(A/ANLs)have aroused great attentions owing to their tunable structure and enhanced mechanical ***,the plastic deformation mechanism of A/ANLs have yet been ***,we systematically examined the mechanical properties and deformation behavior of series of NiNb/ZrCuNi Al A/ANLs via nanoindentaion *** was found that both the amount and morphology of amorphous/amorphous interface(A/AIs)played crucial roles in the plastic deformation of A/*** and straighter A/AIs facilitated multiple shear banding deformation,of which the hardness increased with decreasing layer thickness,as the A/AIs hindered the propagation of shear bands(SBs).whilst,more and wavier A/AIs promoted homogeneous deformation,of which the hardness stayed at a much lower value and was relatively irrelevant with the layer thickness,for the promoted activation of shear transformation zones by A/*** results provide guidance for modifying the mechanical properties of amorphous alloys with interface engineering design.

关键词： Amorphous alloys Nanolaminates Shear bands hardness Interface

Five-fold local symmetry in metallic liquids and glasses

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Chinese Physics B 2017年第1期26卷 10-19页

作者： M Z Li h L Peng Y C hu F X Li h P Zhang w h wang Department of Physics Beijing Key Laboratory of Opto-electronic Functional Materials ＆ Micro-nano Devices Renmin University of China Beijing 100872 China Institute of Physics Chinese Academy of Sciences Beijing 100091 China

The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry.

关键词： metallic glass structure–property relation five-fold local symmetry