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reverse monte carlo study on structural order in liquid and glassy AlFe alloys

Chinese Physics B 2009年第11期18卷 4949-4954页

作者：张景祥李辉张洁宋西贵边秀房 Key Lab of Liquid Structure and Heredity of Materials Ministry of EducationSchool of Materials Science and EngineeringShandong University School of Information Science and Engineering University of Jinan

This paper reports that anomalous local order in liquid and glassy A1FeCe alloy has been detected by x-ray diffraction measurements. The addition of the element Ce has a great effect on this local structural order. The element Ce favours interpenetration of the icosahedra by sharing a common face and edges. It argues that frustration between this short-range order and the long-range crystalline order controls the glass-forming ability of these liquids. The obtained results suggest that a system having a stronger tendency to show local icosahedral order should be a better glass-former. This scenario also naturally explains the close relationship between the local icosahedral order in a liquid, glass-forming ability, and the nucleation barrier. Such topological local order has also been analysed directly using the reverse monte carlo method. It also estimated the fraction of local ordered and disordered structural units in a glassy AlFeCe alloy.

关键词： reverse monte carlo x-ray diffraction (XRD) liquid metal metallic glass

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Research Progress of reverse monte carlo and Its Application in Josephson Junction Barrier Layer

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2077-2109页

作者： Junling Qiu Huihui Sun Shuya Wang State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450001China

As indispensable components of superconducting circuit-based quantum computers,Josephson junctions determine how well superconducting qubits *** monte carlo(RMC)can be used to recreate Josephson junction’s atomic structure based on experimental data,and the impact of the structure on junctions’properties can be investigated by combining different analysis *** order to build a physical model of the atomic structure and then analyze the factors that affect its performance,this paper briefly reviews the development and evolution of the RMC *** also summarizes the modeling process and structural feature analysis of the Josephson junction in combination with different feature extraction techniques for electrical characterization ***,the obstacles and potential directions of Josephson junction modeling,which serves as the theoretical foundation for the production of superconducting quantum devices at the atomic level,are discussed.

关键词： reverse monte carlo Josephson junction alumina barrier layer

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Anomalies in the short-range local environment and atomic diffusion in single crystalline equiatomic CrMnFeCoNi highentropy alloy

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Nano Research 2024年第6期17卷 5336-5348页

作者： Alevtina Smekhova Daniel Gaertner Alexei Kuzmin Ana Guilherme Buzanich Goetz Schuck Ivo Zizak Gerhard Wilde Kirill V.Yusenko Sergiy Divinski Helmholtz-Zentrum Berlin für Materialien und Energie(HZB) D-12489 BerlinGermany Institute of Materials Physics University of MünsterD-48149 MünsterGermany Institute of Solid State Physics University of LatviaLV-1063 RigaLatvia Bundesanstalt für Materialforschung und–prüfung(BAM) D-12489 BerlinGermany

Multi-edge extended X-ray absorption fine structure(EXAFS)spectroscopy combined with reverse monte carlo(RMC)simulations was used to probe the details of element-specific local coordinations and component-dependent structure relaxations in single crystalline equiatomic CrMnFeCoNi high-entropy alloy as a function of the annealing *** representative states,namely a high-temperature state,created by annealing at 1373 K,and a low-temperature state,produced by long-term annealing at 993 K,were compared in *** features identified in atomic configurations of particular principal components indicate variations in the local environment distortions connected to different degrees of compositional disorder at the chosen representative *** detected changes provide new atomistic insights and correlate with the existence of kinks previously observed in the Arrhenius dependencies of component diffusion rates in the CrMnFeCoNi high-entropy alloy.

关键词： high-entropy alloys diffusion short-range order extended X-ray absorption fine structure(EXAFS) reverse monte carlo

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Al-driven peculiarities of local coordination and magnetic properties in single-phase Al_(x)-CrFeCoNi high-entropy alloys

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Nano Research 2022年第6期15卷 4845-4858页

作者： Alevtina Smekhova Alexei Kuzmin Konrad Siemensmeyer Chen Luo Kai Chen Florin Radu Eugen Weschke Uwe Reinholz Ana Guilherme Buzanich Kirill V.Yusenko Helmholtz-Zentrum Berlin für Materialien und Energie(HZB) D-12489Germany Institute of Solid State Physics University of LatviaLV-1063Latvia Bundesanstalt für Materialforschung und-prüfung(BAM) D-12489Germany

Modern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic ***,peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic(fcc)-and body-centered cubic(bcc)-structured high-entropy Alx-CrFeCoNi alloys(x=0.3 and 3,respectively)are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy *** based on the reverse monte carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high *** revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry.A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account.X-ray magnetic circular dichroism technique employed at L2,3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk *** to nanostructured versions of multicomponent alloys,such studies would bring new insights related to effects of high entropy mixing on low dimensions.

关键词： high-entropy alloys reverse monte carlo magnetism element-specific spectroscopy extended X-ray absorption fine structure(EXAFS) X-ray magnetic circular dichroism(XMCD)

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Calculation of radiative heat flux on irregular boundaries in participating media

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Chinese Physics B 2020年第12期29卷 322-328页

作者： Yu-Jia Sun Shu Zheng School of Atmospheric Physics Nanjing University of Information Science and TechnologyNanjing 210044China National Engineering Laboratory for Biomass Power Generation Equipment North China Electric Power UniversityBeijing 102206China

Radiative heat flux at wall boundaries is important for its thermal *** methods based on structured grids are becoming trendy due to their simplicity and *** radiative transfer equation solvers produce oscillating radiative heat flux at the irregular boundary if they are based on structured *** monte carlo method and analytical discrete ordinates method are adopted to calculate the radiative heat flux at complex *** results show that the reverse monte carlo method can generate a smooth radiative heat flux profile and it is smoother with larger energy *** results from the analytical discrete ordinates method show that the fluctuations are due to the ray *** the total or the mean radiative heat flux,the results from the analytical discrete ordinates method are very close to those from the reverse monte carlo method.

关键词： radiative heat flux reverse monte carlo irregular boundary

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Cu基大块非晶合金的制备及Pd基非晶的结构研究

Cu基大块非晶合金的制备及Pd基非晶的结构研究

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作者：徐潇浙江大学

学位级别：硕士

自从上个世纪六十年代美国加州理工大学的Duwez等人用熔体快冷的方法制得了Au-Si非晶合金后,非晶态金属独特的物理性能、化学性能、机械性能和防腐蚀性能引起了广泛的关注和极大的兴趣。近年来,Cu基非晶合金以其低廉的成本,很强的非晶... 详细信息

自从上个世纪六十年代美国加州理工大学的Duwez等人用熔体快冷的方法制得了Au-Si非晶合金后,非晶态金属独特的物理性能、化学性能、机械性能和防腐蚀性能引起了广泛的关注和极大的兴趣。近年来,Cu基非晶合金以其低廉的成本,很强的非晶形成能力以及优良的力学性能逐渐引起人们的关注。Pd基非晶合金是人们较早开发出来的大块非晶合金,其最大尺寸可达70cm以上。本论文主要围绕以上两个体系,做了以下研究: 1.研究了CuZrAlRE,(RE=La,Ce,Nd and Gd,0≤x≤5 at.%)体系的非晶形成能力和热力学性质,发现在该体系中非晶形成能力最好的成分CuZrAlGd并不是共晶成分。引入了γ参数来评价非晶形成能力。 2.通过在Cu-Zr-Al体系中加入微量稀土元素,成功的改善了体系的非晶形成能力,找到了cm级的Cu基大块非晶合金CuZrAlGd。说明微合金化对非晶形成能力的提高有很大的帮助。 3.通过研究加入稀土元素后体系对真空度的敏感性,发现稀土元素的加入能有效的降低环境中的氧对体系非晶形成的破坏作用,这使得在低真空下开发大块非晶合金成为可能。 4.研究了Ca-Zr-Al-RE体系的力学性能。发现CuZrAl(x=1,2,3)三元体系有良好的塑性。进一步比较了不同的制备工艺对力学性能的影响。不同的制备工艺使得样品的微观结构发生了改变,进而影响了非晶的力学性能。 5.主要应用同步辐射手段对PdNiP,PdCuNiP两种非晶形成能力很强的成分进行了研究。通过比较不同温度下的S(Q)峰位和强度,我们发现S(Q)的强度随着温度的变化有一突变,这一突变温度对应于玻璃转变温度。 6.我们用MCGR软件来模拟得到非晶的总径向分布函数,并比较了PdNiP和PdCuNiP的近邻结构,发现Pd基非晶中可能存在具有五次对称轴的二十面体结构。正是这种结构使得非晶具有良好的形成能力。随着Cu原子的加入,原子的密堆程度更高,这也是PdCuNiP具有更强非晶形成能力的原因之一。 7.利用同步辐射原位观测了PdNiP的晶化过程。发现其晶化分两个阶段,

关键词：大块非晶非晶形成能力力学性能铜基非晶合金径向分布函数 reverse monte carlo 模拟

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