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基于模拟-建模研究化学与温度对难熔高熵合金力学行为和变形机制的影响

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Acta Mechanica Sinica 2024年第2期40卷 103-115页

作者：李甲任思危刘彬 peter k.liaw 方棋洪 State key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China State key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China Department of Materials Science and Engineering The University of TennesseeKnoxville37996USA

难熔高熵合金在高温下表现出优异的性能,突破了传统高温合金的工作温度上限.我们采用原子模拟研究了化学元素分布和温度对等原子比MoNbTaW难熔高熵合金变形机制的影响.根据微观结构演化,建立了基于微观结构的本构模型,定量评估多种强化... 详细信息

难熔高熵合金在高温下表现出优异的性能,突破了传统高温合金的工作温度上限.我们采用原子模拟研究了化学元素分布和温度对等原子比MoNbTaW难熔高熵合金变形机制的影响.根据微观结构演化,建立了基于微观结构的本构模型,定量评估多种强化机制的贡献.结果表明,应变硬化后,流动应力随应变呈锯齿状剧烈波动.由于退火结构的溶质浓度降低,温度升高降低了应变硬化率和流动应力波动幅度.变形孪晶在变形机制中起着关键作用,能够通过位错基塑性和晶粒中的非晶形核进一步调节局部变形.有序结构的存在强烈影响了应力和应变分配.固溶强化和晶界强化对流动应力的贡献很大,孪晶强化对流动压力的贡献很小.原子模拟和力学模型为深入理解难熔高熵合金变形行为及性能的精确预测提供依据.

关键词：流动应力固溶强化强化机制高温合金高熵合金变形机制晶界强化溶质浓度

Achieving strength–ductility synergy in novel paramagnetic Fe-based medium-entropy alloys through deep cryogenic deformation

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Rare Metals 2024年第9期43卷 4493-4507页

作者： Hu-Wen Ma Yan-Chun Zhao Li Feng Tian-Zeng Liu Zhi-Qi Yu Bo Jin Wang-Chun Duan peter k.liaw Dong Ma State key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals Lanzhou University of Technology Wenzhou Pump and Valve Engineering Research Institute Lanzhou University of Technology Iron and Steel Research Institute Jiuquan Iron and Steel Corporation Lanzhou Resources and Environment Voc-Tech University Department of Materials Science and Engineering The University of Tennessee Neutron Science Center Songshan Lake Materials Laboratory

Cryogenic pre-deformation treatment has been widely used to effectively improve the comprehensive mechanical properties of steels and novel metals. However,the dislocation evolution and phase transformation induced by different degrees of deep cryogenic deformation are not yet fully elucidated. In this study, the effects of multiple cryogenic pre-treatments on the mechanical properties and deformation mechanisms of a paramagnetic Fe63.3Mn14-Si9.1Cr9.8C3.8medium-entropy alloy（MEA） were investigated, leading to the discovery of a pretreated MEA that exhibits exceptional mechanical properties, including a fracture strength of 3.0 GPa, plastic strain of 26.1% and work-hardening index of 0.57. In addition, X-ray diffraction（XRD） and transmission electron microscopy（TEM）analyses revealed that multiple cryogenic pre-deformation treatments significantly increased the dislocation density of the MEA(from 9 × 1015to 4 × 1016m-2after three pretreatments), along with a transition in the dislocation type from predominantly edge dislocations to mixed dislocations（including screw-and edge-type dislocations）. Notably, this pretreated MEA retained its paramagnetic properties（μrking fault energy of the MEA by a factor of approximately four(i.e., from 9.7 to2.6 m J·m-2), thereby activating the synergistic effects of transformation-induced plasticity, twinning-induced plasticity and dislocation strengthening mechanisms. These synergistic effects lead to simultaneous strength and ductility enhancement of the MEA.

关键词： Deep cryogenic transformation Dislocation evolution Iron-based medium-entropy alloys Phase transformation Stacking fault energy

Effect of Magnetic Field Configuration on Stray-Crystal Formation with Different Platform Sizes during Directional Solidification of Single-Crystal Superalloy

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 904-914页

作者： keke Lu Congjiang Zhang Xiaotan Yuan Hongbin Yu Weili Ren Biao Ding Haibiao Lu Yunbo Zhong Zuosheng Lei Hui Wang Qiuliang Wang peter kliaw Xuezhi Qin Lanzhang Zhou State key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced FerrometallurgyShanghai UniversityShanghai 200444China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The magnetic field is an effective means to control the solidification structure and the defects of metal and semiconductor *** work investigates the effects of Cusp magnetic field(CMF)and longitudinal magnetic field(LMF)on the stray-crystal formation in the platform regions during the directional solidification of single-crystal superalloy with the different cross section *** application of CMF reduces the formation of platform stray-crystal,while LMF increases its *** the platform size increases,the stray-crystal ratio increases regardless of whether the magnetic fields are applied or not,the effectiveness of CMF increases,while that of LMF *** reason that the effects of CMF and LMF on the platform stray-crystal formation could be attributed to the change of flow structure from the distribution characteristics of the thermoelectric magnetic force and the magnetic damping force near the liquid-solid interface.

关键词： Stray-crystal Magnetic field Single-crystal superalloy Cross section change Directional solidification

Structure design and property of multiple-basis-element(MBE)alloys flexible films

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Nano Research 2022年第6期15卷 4837-4844页

作者： Hao Huang peter k.liaw Yong Zhang Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming Qinghai UniversityXining 810016China State key Laboratory of Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996-2100USA Shunde Graduate School University of Science and Technology BeijingFoshan 528399China

A controlled wrinkled structure is a simple and effective approach to achieve unique properties and has been widely used in flexible *** this study,we reported a substrate prestrain method for fabricating wrinkle-structured Zr52Ti34Nb14 multiplebasis-element(MBE)alloy films as biocompatible *** in the film thickness and substrate prestraining enabled a precise control of the amplitude and wavelength of the wrinkled structures,ranging from micrometers to ***,owing to the flexibility of the wrinkled structures,the wrinkle-structure pattern could be adjusted by simply relaxing or further stretching of the substrate,leading to dynamically tunable transmittance and wetting *** result not only reveals Zr52Ti34Nb14 MBE alloy films as a potential flexible material,but also provides a new structural design approach for other MBE alloy systems.

关键词： multiple-basis-element alloy thin films microstructures optical transmission wetting behavior

Ultrastrong and ductile BCC high-entropy alloys with low-density via dislocation regulation and nanoprecipitates

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Journal of Materials Science & Technology 2022年第15期110卷 109-116页

作者： Xuehui Yan peter k.liaw Yong Zhang Beijing Advanced Innovation Center of Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996United States of America

The high strength is a typical advantage of body-centered-cubic high-entropy alloys(BCC–HEAs).However,brittleness and weak strain-hardening ability are still their Achilles'***,extraordinary strength together with good tensile ductility are achieved in(Zr_(0.5)Ti_(0.35)Nb_(0.15))_(100-x)Al_(x) alloys(at.%,x=10 and 20)at room *** low densities of less than 6 g/cm^(3)are exhibited in these *** nanoprecipitates and diversifying dislocation motions are the keys to achieving such salient *** is worth noting that the tensile strength of 1.8 GPa in(Zr_(0.5)Ti_(0.35)Nb_(0.15))_(80)Al_(20)alloy is a record-high value known in reported BCC–HEAs,as well as a tensile strain over 8%.Furthermore,the maximum strain of~25%in(Zr_(0.5)Ti_(0.35)Nb_(0.15))_(90)Al_(10)alloy can challenge existing limit value,and is accompanied with a tensile strength of 1.2 *** current work does not only provide novel ultra-strong and tough structural materials with low density,but also sheds new light on designing BCC–HEAs with attractive performances and strain-hardening ability.

关键词： High-entropy alloys Mechanical properties Dislocation Nanoprecipitates Strain hardening

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Nanoscale fluctuation of stacking fault energy strengthens multi-principal element alloys

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Journal of Materials Science & Technology 2023年第27期158卷 218-225页

作者： Zongrui Pei Markus Eisenbach peter k.liaw Mingwei Chen New York University New York 10012USA Oak Ridge National Laboratory Oak RidgeTennessee 37831USA Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA Department of Materials Science and Engineering Johns Hopkins UniversityBaltimoreMaryland 21218USA Engineering and Hopkins Extreme Materials Institute Johns Hopkins UniversityBaltimoreMaryland 21218USA

Chemical randomness and the associated energy fluctuation are essential features of multi-principal ele-ment alloys(MPEAs).Due to these features,nanoscale stacking fault energy(SFE)fluctuation is a natural and independent contribution to strengthening ***,existing models for conventional alloys(i.e.,alloys with one principal element)cannot be applied to *** extreme values of SFEs required by such models are unknown for MPEAs,which need to calculate the nanoscale volume relevant to the SFE *** the present work,we developed an analytic model to evaluate the strengthening ef-fect through the SFE fluctuation,profuse in *** model has no adjustable parameters,and all parameters can be determined from experiments and ab initio *** model explains available experimental observations and provides insightful guidance for designing new MPEAs based on the SFE *** generally applies to MPEAs in random states and with chemical short-range order.

关键词： Nanoscale energy fluctuation Staking fault energy Chemical short-range order Multi-principal element alloy Mechanism

A Brief Review of High Entropy Alloys and Serration Behavior and Flow Units

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Journal of Iron and Steel Research International 2016年第1期23卷 2-6页

作者： Yong ZHANG Jun-wei QIAO peter k.liaw State key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Laboratory of Applied Physics and Mechanics of Advanced Materials College of Materials Science and EngineeringTaiyuan University of Technology Department of Materials Science and Engineering University of Tennessee

Multicomponent alloys with high entropy of mixing,e.g.,high entropy alloys（HEAs）and/or multiprincipal-element alloys（MEAs）,are attracting increasing attentions,because the materials with novel properties are being developed,based on the design strategy of the equiatomic ratio,multicomponent,and high entropy of mixing in their liquid or random solution ***,HEAs with the ultrahigh strength and fracture toughness,excellent magnetic properties,high fatigue,wear and corrosion resistance,great phase stability/high resistance to heat-softening behavior,sluggish diffusion effects,and potential superconductivity,etc.,were *** HEAs can even have very high irradiation resistance and may have some self-healing effects,and can potentially be used as the first wall and nuclear fuel cladding *** behaviors and flow units are powerful methods to understand the plastic deformation or fracture of *** methods have been successfully used to study the plasticity of amorphous alloys（also bulk metallic glasses,BMGs）.The flow units are proposed as：free volumes,shear transition zones（STZs）,tension-transition zones（TTZs）,liquid-like regions,soft regions or soft spots,*** flow units in the crystalline alloys are usually dislocations,which may interact with the solute atoms,interstitial types,or substitution ***,the flow units often change with the testing temperatures and loading strain rates,e.g.,at the low temperature and high strain rate,plastic deformation will be carried out by the flow unit of twinning,and at high temperatures,the grain boundary will be the weak area,and play as the flow *** serration shapes are related to the types of flow units,and the serration behavior can be analyzed using the power law and modified power law.

关键词： high entropy alloy bulk metallic glass serration behavior flow unit

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Mining of lattice distortion, strength, and intrinsic ductility of refractory high entropy alloys

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npj Computational Materials 2023年第1期9卷 1814-1825页

作者： Christopher Tandoc Yong-Jie Hu Liang Qi peter k.liaw Department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA 19104USA Department of Materials Science and Engineering University of MichiganAnn ArborMI 48109USA Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA

Severe lattice distortion is a prominent feature of high-entropy alloys(HEAs)considered a reason for many of those alloys’***,accurate characterizations of lattice distortion are still scarce to only cover a tiny fraction of HEA’s giant composition space due to the expensive experimental or computational *** we present a physics-informed statistical model to efficiently produce high-throughput lattice distortion predictions for refractory non-dilute/high-entropy alloys(RHEAs)in a 10-element composition *** model offers improved accuracy over conventional methods for fast estimates of lattice distortion by making predictions based on physical properties of interatomic bonding rather than atomic size mismatch of pure *** modeling of lattice distortion also implements a predictive model for yield strengths of RHEAs validated by various sets of experimental *** our previous model on intrinsic ductility,a data mining design framework is demonstrated for efficient exploration of strong and ductile single-phase RHEAs.

关键词： alloys ductility strength

Tensile deformation behavior and mechanical properties of a bulk cast Al0.9 CoFeNi2 eutectic high-entropy alloy

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Journal of Materials Science & Technology 2021年第2期61卷 119-124页

作者： Hui Jiang Dongxu Qiao Wenna Jiao kaiming Han Yiping Lu peter k.liaw College of Mechanical and Electronic Engineering Shandong University of Science and TechnologyQingdao 266590China key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Stare key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Department of Materials Science and Engineering the University of TennesseeKnoxvilleTN37996USA

In this study,a new Al0.9CoFeNi2 eutectic high entropy alloy(EHEA) was designed,and the microstructures as well as the deformation behavior were *** bulk cast Al0.9CoFeNi2 EHEA exhibited an order face-centered cubic FCC(L12) and an order body-centered cubic(B2) dual-phase lamellar eutectic *** volume fractions of FCC(L12) and B2 phases are measured to be 60 % and 40 %,*** combination of the soft and ductile FCC(L12) phase together with the hard B2 phase resulted in superior strength of 1005 MPa and ductility as high as 6.2 % in tension at room *** Al0.9CoFeNi2 EHEA exhibited obvious three-stage work hardening characteristics and high workhardening *** evolving dislocation substructure s during uniaxial tensile deformation found that planar slip dominates in both FCC(L12) and B2 phases,and the FCC(L12) phase is easier to deform than the B2 *** post-deformation transmission electron microscopy revealed that the sub-structural evolution of the FCC(L12) phase is from planar dislocations to bending dislocations,high-density dislocations,dislocation network,and then to dislocation walls,and Taylor lattices,while the sub-structural evolution of the B2 phase is from a very small number of short dislocations to a number of planar ***,obvious ductile fracture in the FCC(L12) phase and a brittle-like fracture in the B2 phase were observed on the fracture surface of the Al0.9CoFeNi2 *** re search results provide some insight into the microstructure-property relationship.

关键词： Eutectic high-entropy alloy Microstructure Mechanical properties Deformation behavior

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