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Amorphization of Co-Nb Magnetic Alloys by Mechanical Alloying

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Chinese Physics Letters 1991年第8期8卷 436-438页

作者： MA Xueming YUE Lanping dong yuanda Institute of Solid State Physics Academia SinicaHefei 230031

Formation of amorphous Co-Nb system by mechanical alloying(MA)in the composition range of Co_(25)Nb_(75)-Co_(70)Nb_(30) was studied by X-ray *** properties of the mechanically alloyed Co_(70)Nb_(30) powder were *** variation in H_(c) curve with milling time can be explained by two-stage mechanism involved in the milling *** results show that the amorphous powder prepared by MA is of good soft magnetic properties.

关键词： diffraction properties process

Influence of Milling Conditions on the Mechanical Alloying of Fe-B Powders

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Journal of Materials Science & Technology 1999年第2期15卷 137-142页

作者： Yang, Yuanzheng Li, Qiaoshen Zhu, Youlan Ma, Xueming dong, yuanda Guangdong Univ Technol Dept Mat Sci & Engn Guangzhou 510090 Peoples R China Shanghai Univ Dept Mat Sci & Engn Shanghai 200072 Peoples R China

Amorphous and nanostructural Fe-B alloys made by mechanical alloying of elemental Fe and amorphous B powders have been studied using X-ray diffraction, differential scanning calorimetry and Mossbauer spectroscopy. It has been shown that the milling conditions have a strong effect on the alloying. The single phase amorphous alloy, which is limited at nominal composition of Fe//6//0B//4//0, has been produced only by milling in Ar atmosphere and in other composition range the mixture of nanostructure Fe-like phase and Fe//2B compound with a little amorphous phase were obtained. While by milling in air atmosphere the introduction of oxygen in air may suppress the formation of amorphous phase, thus the compounds Fe//2B may be synthesized with no trace of amorphous phase. The crystallization temperatures of amorphous phase in the resultant products are higher than those of a single amorphous alloy Fe//6//0B//4//0, and hardly independent of the milling conditions and the composition. In addition, it is revealed that detectable B content in the final products is lower than the nominal composition of all the initial samples, which indicates that some B atoms may be located in the disordered interfacial regions of the nano-structural alloyed mixtures. (Edited author abstract) 12 Refs.

关键词： Iron alloys

FORMATION OF AMORPHOUS Al_(80)Fe_(20)BY MECHANICAL ALLOYING

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Acta Metallurgica Sinica(English Letters) 1991年第8期4卷 93-97页

作者： WANG Weihua XIAO Keqin CHU Zhaoqin dong yuanda WANG Gengmiao Institute of Solid State Physics Academia Sinica Centre of Structural Analysis China University of Science and Technology

Amorphous Al_(80)Fe_(20) powder which can hardly be obtained using conventional rapid quenching technique was directly prepared from crystalline Fe and A1 powders by means of mechanical alloying *** amorphization process was examined by X-ray analysis and Mssbauer spectroscopy,and the thermal behaviour was studied by *** results show that the rate of amorphization is controlled by the diffusion reaction at the interfaces and changes with the milling *** effect of milling conditions on amorphization by mechanical alloying was al- so investigated.

关键词： mechanical alloying amorphization Al-Fe amorphous alloy Mossbauer spectrum analysis

Investigation of Amorphization of Nb-Si Alloys by Mechanical Alloying

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Chinese Physics Letters 1994年第11期11卷 681-684页

作者： LI Bing MA Xueming LIU Lin QI Zhenzhong dong yuanda Institute of Solid State Physics Academia SinicaHefei 230031 Department of Metallurgy and Materials Shanghai University of TechnologyShanghai 200072

Amorphous Nb_(62.5)Si_(37.5) and Nb_(75)Si_(25) alloys were produced from mixtures of elemental Nb and Si powders by mechanical alloying(MA).The structural changes of mechanically alloyed powders were monitored by x-ray *** was found that NbSi_(2),intermetallic compound was formed in the initial stage of MA of or Nb_(62.5)Si_(37.5) or Nb_(75)Si_(25) *** continued milling,the mixtures of intermetallic NbSi_(2) and elemental Nb transformed into amorphous Nb-Si alloys(Nb_(62.5)Si_(37.5) or Nb_(75)Si_(25)).The slow interdiffusion of Nb and Si and the slower diffusion of silicon atoms to niobium matrix than that of niobium atoms to silicon matrix were suggested to be responsible for the formation of intermetallic NbSi_(2).The amorphization of 3NbSi_(2)+7Nb mixtures(or NbSi_(2)+5Nb mixtures)is believed to be controlled by material transfer,which moves composition of line intermetallic NbSi2 off stoichiometry,and causes the matrix of elemental Nb deformed.

关键词： intermetallic alloys alloying

Discovering Latent Variables for the Tasks With Confounders in Multi-Agent Reinforcement Learning

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1591-1604页

作者： Kun Jiang Wenzhang Liu yuanda Wang Lu dong Changyin Sun the School of Automation Southeast UniversityNanjing 210096China the School of Artificial Intelligence Anhui UniversityHefei 230601China IEEE the School of Cyber Science and Engineering Southeast UniversityNanjing 211189China the Engineering Research Center of Autonomous Unmanned System Technology Ministry of EducationHefei 230601China

Efficient exploration in complex coordination tasks has been considered a challenging problem in multi-agent reinforcement learning(MARL). It is significantly more difficult for those tasks with latent variables that agents cannot directly observe. However, most of the existing latent variable discovery methods lack a clear representation of latent variables and an effective evaluation of the influence of latent variables on the agent. In this paper, we propose a new MARL algorithm based on the soft actor-critic method for complex continuous control tasks with confounders. It is called the multi-agent soft actor-critic with latent variable(MASAC-LV) algorithm, which uses variational inference theory to infer the compact latent variables representation space from a large amount of offline ***, we derive the counterfactual policy whose input has no latent variables and quantify the difference between the actual policy and the counterfactual policy via a distance function. This quantified difference is considered an intrinsic motivation that gives additional rewards based on how much the latent variable affects each agent. The proposed algorithm is evaluated on two collaboration tasks with confounders, and the experimental results demonstrate the effectiveness of MASAC-LV compared to other baseline algorithms.

关键词： Latent variable model maximum entropy multi-agent reinforcement learning(MARL) multi-agent system

MECHANICAL REDUCTION OF CuO BY Mg AT ROOM TEMPERATURE

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Acta Metallurgica Sinica(English Letters) 1992年第3期5卷 218-220页

作者： MA Xueming YUE Lanping dong yuanda Institute of Solid State Physics,Academia Sinica,Hefei,China Inst of Solid State Physics Acad Sinica Hefei China

The mechanical reduction of CuO by pure metallic Mg has been investigated during pulver- izing in ball mill at room *** reduction was towards its completion of an average particle size down to 20 nm after milling for 32 *** mechanism of the mechanical reduction of oxides seems to be the surface activation of nano-metre sized particles driven by mechani- cal force.

关键词： CuO Cu mechanical reduction Mg

FORMATION OF AMORPHOUS Cu_(60)Zr_(40)AND Ni_(50)Zr_(50)POWDERS BY MECHANICAL ALLOYING

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Chinese Physics Letters 1989年第5期6卷 229-232页

作者： dong yuanda XIAO Keqin LIU Lin WU Ziqiang WANG Weihua HE Yizhen Institute of Solid State Physics Academia SinicaHefei

Amorphization of Cu-Zr and Ni-Zr systems by mechanical alloying(MA)was studied by X-ray *** results show that the amorphization is not merely a simple interdiffusion by thermal activation;in addition,the strain induce... 详细信息

关键词： diffraction. alloying process.

Mechanically-driven Amorphization in Metallic Systems

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Journal of Materials Science & Technology 1993年第3期9卷 161-166页

作者： yuanda dong Dept.of Metallurgy and Materials,Shanghai University of Technology,Shanghai,200072,China

The mechanism of mechanically-driven amorphization was extensively surveyed in various systems. It was concluded that the amorphization could occur in the systems of Cu-Zr with a negative heat of mixing (-ΔH) and Cu-Ta with a positive heat of mixing (+ΔH) by mechanical alloying of elemental *** amorphization could also be started from an intermetallic compound Cu_xZr_y with no chemical reaction *** energy storage by mechanical attrition should be the driving force for the *** atomic distribution function and nuclear resonance spectroscopic studies show that the mechanical alloying provides a true alloying on an atomic *** alloys formed are of a characteristic structure common to the rapidly quenched amorphous alloys.

关键词： mechanically-driven amorphization metallic system Cu-Zr Cu-Ta

Structural Characteristics of Rapidly Quenched Al-Si Alloys

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Journal of Materials Science & Technology 1994年第3期10卷 232-234页

作者： Lin LIU(Institute of Solid State Physics, Academia Sinica, Hefei, 230031, China)yuanda dong(Dept. of Metallurgy and Materials, Shanghai University of Technology, Shanghai, 200072, China) Inst of Solid State Physics Academia Sinica Hefei China

The structure of rapldly quenched Al-Si alloys (1 and 4 wt-%Si) was systematically studied by optical and transmission electron microscopy (TEM ) as welI as X-ray djffractjon (XRD). ExperimentaIresults show that rapid solidification refines the grain size. extends the solid solubility of Si in Al and Introduces a high density ot defects which exist in the forms of vacancies, dislocations and dislocation loops. etc.. The decomposition process of the alloys was fol lowed by using differential scanning calorimeter (DSC) and the activation energy for precipitation of Si was obtained through Kissinger analysis. The precipitation behaviour of Supersaturated Si in both samples was further examined by TEM. It was found that Si mainly precipitated inside the grains in Al-1 wt-%Si alloy. while in Al-4 wt-%Si alloy. nearly all the Si precipitates distributed along the grain boundaries. This may be due to the structure difference between the alloys in as-quenched state

关键词： Al Si Structural Characteristics of Rapidly Quenched Al-Si Alloys