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Progress of Nonequilibrium Solidification Theory

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Journal of Materials Science & Technology 1998年第6期14卷 497-505页

作者： Li, Qingchun Cui, Chengsong Xu, Daming yuan, xiaoguang Harbin Inst Technol Harbin 150001 Peoples R China Jilin Univ Technol Changchun 130025 Peoples R China

The theory related to nucleation, interface kinetics, micromorphology evolution and microscopic growth during nonequilibrium alloy solidification was reviewed. Methods for quantitative analysis of nucleation rate, the criterion of marginal stability, nonequilibrium partition coefficient, as well as the relationship between growth rate with undercooling and dendrite tip radius were presented. Some limitations and future developments of nonequilibrium theory were presented. (Edited author abstract) 55 Refs.

关键词： Alloys

Microstructure and mechanical properties of hypereutectic Al-Fe alloys prepared by semi-solid formation

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China Foundry 2011年第4期8卷 424-431页

作者： Liu Bo yuan xiaoguang Huang Hongjun School of Materials Science and Engineering Shenyang University of Technology Shenyang 110870 China School of Naval Architecture and Civil Engineering Zhejiang Ocean University Zhoushan 316000 China

The effects of alloying elements, electromagnetic stirring, reheating and semi-solid formation on the microstructure and mechanical properties of Al-Fe alloys prepared by semi-solid formation were studied. It was found that alloying elements and electromagnetic stirring can alter the morphology and growth mode of the iron-rich phase in Al-Fe alloys; and effectively refine the primary Al3Fe phase. In contrast to the microstructure obtained in conventional casting, the Al3Fe phase becomes thin short rod-like instead of thick needle-like; and the dendritic grain structure almost disappears in the semi-solid formation. The Al3Fe phase can be further refined through being dissolved or fused during subsequent reheating. It was also found that the larger extrusion ratio of semi-solid formation causes a greater crushing effect and therefore the Al3Fe phase is more refined and has more uniform distribution. Moreover, Al-Fe alloys prepared by semi-solid formation exhibit excellent mechanical properties at both room and high temperatures.

关键词： Al-Fe alloy semi-solid formation microstructure mechanical property

Microstructure and Properties of Spray Deposited 2024-20Si-5Fe Alloy

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Journal of Materials Science & Technology 1998年第5期14卷 402-406页

作者： yuan, xiaoguang Ren, Luquan Cui, Chengsong Xu, Daming Li, Qingchun Jilin Univ Technol Engn Bion Res Inst Changchun 130025 Peoples R China Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

A rapidly solidified Al-Si-Fe-Cu-Mg alloy was prepared by spray deposition. The microstructure of the alloy includes silicon phase and delta -(Al,Fe,Si), Al//8Si//6Mg//3Fe, FeAl//2 and small FeSi//2 phases. The reasons of the formation of silicon and delta -(Al,Fe,Si) phase were analyzed. The tensile properties at the room temperature to 350 degree C were investigated, and the strengthening mechanism was suggested. The wear resistance and cutability of the alloy were measured as well. (Edited author abstract) 11 Refs.

关键词： Aluminum alloys

Infuence of Liquid Film Characteristics on Hot Cracking Initiation in Al–Cu Alloys at the End of Solidifcation

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Acta Metallurgica Sinica(English Letters) 2023年第1期36卷 103-117页

作者： Ming Su xiaoguang yuan Chunyu Yue Wentao Zheng Yuxiang Wang Jian Kang School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

In this study,Al–4Cu alloy specimens with spherical grains and liquid flms were obtained by isothermal reheating *** hot cracking of the solidifcation process was determined using a modifed constrained rod casting experimental apparatus,and the efect of liquid flm characteristics at the end of solidifcation on hot cracking initiation of Al–4Cu alloys was systematically investigated by combining molecular dynamics simulations and other *** the extension of soaking time,the liquid fraction(liquid flm fraction at the end of solidifcation)and grain shape factor increased with higher isothermal reheating ***,the widened flling channel decreased the hot cracking initiation temperature and the critical hot cracking shrinkage stress was found to increase,thus reducing the hot cracking severity in Al–4Cu *** dynamics simulations revealed that with the extension of soaking time,the composition of the liquid flm changed at diferent isothermal reheating temperatures,but the short-range structure and atomic ordering of the liquid flm remained the *** activity of the liquid flm increased in equilibrium,leading to a decrease in viscosity and an increase in fuidity,which contributed to the flling *** isothermal reheating at 640℃for 60 min,the liquid fraction reached the maximum,and the viscosity of the liquid flm was the *** addition,almost no hot cracks were found.

关键词： Al-4Cu alloy Liquid flm characteristics Isothermal reheating Molecular dynamics simulation Hot cracking initiation mechanism

Hot Deformation Behaviors in Ti-6Al-4V/(TiB+TiC)Composites

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Acta Metallurgica Sinica(English Letters) 2021年第12期34卷 1747-1757页

作者： Xuejian Lin Hongjun Huang Fuyu Dong Yue Zhang xiaoguang yuan Bowen Zheng Xiaojiao Zuo School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

Thermal compression testing was investigated using the Gleeble 3800 thermal simulator,and thermal deformation behavior of particle-reinforced titanium matrix composites(TMCs)was studied under deformation temperatures of 750-900°C,strain rates of 0.001-1 s^(-1),and experimental deformation of 60%.According to obtained flow stress curves,the hot deformation characteristics were *** on the Arrhenius hyperbolic sinusoidal model,the constitutive equation at high temperature was *** on the theory of dynamic material models,a hot processing map of TMCs at high temperature was established,and the peak region of power dissipation rate and the instability region in the hot processing map were both *** the same time,the corresponding microstructures in the peak power dissipation rate and rheological instability regions were *** results showed that flow stress decreased with increasing deformation temperature and increased with increasing strain *** thermal deformation activation energy of titanium matrix composites was 301.8 kJ/*** Ti-6Al-4V/(TiB+TiC)composites possessed only one instability zone under high-temperature compression at a strain of 0.5,with corresponding temperatures at 750-840°C and strain rates at 0.1-1 s^(-1).The optimal thermal deformation parameters included corresponding temperatures of 830-880°C and strain rates of 0.001-0.05 s^(-1).The microstructures corresponding to optimal hot working parameters in processing maps were more homogeneous than the microstructures in the instability zone,including the distribution uniformity of reinforcement and the degree of dynamic recrystallization,and no instability phenomena including abnormal grain growth,microcracks or intensive fracture of reinforcements were found,indicating that the hot processing map had a positive guiding effect on the option of desirable material thermal-working parameters.

关键词： Ti-6Al-4V/(TiC+TiB)composites Hot deformation Flow stress behavior Processing map

A Hot Cracking Initiation Criterion Based on Solidification Liquid Film Characteristic and Microstructure

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Acta Metallurgica Sinica(English Letters) 2023年第11期36卷 1776-1790页

作者： Ming Su Wentao Zheng Chunyu Yue Bowen Zheng Xiaojiao Zuo Mengyuan He xiaoguang yuan School of Materials Science and Engineering Shenyang University of TechnologyShenyang110870China School of Materials Science and Engineering Northeastern UniversityShenyang110870China

Herein,a hot cracking initiation criterion based on the characteristics of solidification liquid film and the microstructure was proposed,which integrated both the mechanical and non-mechanical factors during *** criterion also took the effect of the shrinkage volume of the solid-liquid two-phase in the mushy zone,the flow behavior of the liquid film and the microstructure on the feeding behavior into ***,the effect factors of hot cracking initiation such as alloy composition,microstructure,mold design and process condition were included in this criterion,and it could quantitatively calculate whether hot cracks occurred under a certain state or not during *** criterion was utilized to predict whether hot cracks occurred in Al-4.0 wt%Cu alloy in different initial solidification states or not,which was consistent with the experimental results and verified its *** to the criterion expression,Vfeeding*was related with five effect factors includingη,ΔP*,l*,r*and n,in which r*and n were in positive correlation with Vfeeding*whileη,ΔP*and l*were in negative correlation with that,which provided a good instructive significance for mold design,process optimization and composition and microstructure regulation of alloys and simultaneously further enriched the mechanism and influencing factors of hot cracking ***,a multiscale simulation method for calculating the characteristic parameters of hot tearing behavior during solidification was also provided in this study.

关键词： Hot cracking criterion Liquid film characteristic Microstructure Aluminum alloy Multiscale simulation

Characterization of the asymmetric evolving yield and flow of 6016-T4 aluminum alloy and DP490 steel

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Journal of Materials Science & Technology 2023年第2期133卷 209-229页

作者： Kai Du Shaohui Huang Yong Hou Haibo Wang Yinxiao Wang Wentao Zheng xiaoguang yuan School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China Department of Technical Planning Press Shop BMW Brilliance Automotive Ltd.Shenyang 100044China Department of Materials Science and Engineering&RIAM Seoul National UniversitySeoul 08826Republic of Korea School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China

6016-T4 aluminum alloy and DP490 steel were systematically tested under 24 proportional loading paths,including uniaxial tensile tests with a 15°increment,uniaxial compressive and simple shear tests with a 45°increment,and biaxial tensile tests using cruciform *** specimens in the rolling/transverse and 45°/135°sampling directions were tested with seven and four different stress ra-tios,*** normal and diagonal planes plastic work contours and the yield stresses under uniaxial tension and compression were measured to investigate the anisotropic ***,the normal and diagonal planes directions of plastic strain rate and the rα-values under uniaxial tension and compression were characterized to confirm the plastic *** existing asymmetric yield crite-ria under the associated and non-associated flow rules were comprehensively evaluated to describe the asymmetric plastic anisotropy of 6016-T4 aluminum alloy and DP490 *** results suggest that in the investigated yield criteria,the non-associated models can predict the tension and compression asym-metry of materials more accurately than the associated models,and the function of stress triaxiality can more effectively describe the asymmetric yield behavior than the first stress *** addition,the pure shear stress states are helpful in assessing the validity and applicability of advanced asymmetric yield stress functions,and the inspection of diagonal plane plastic work contours containing more pure shear stress states should prioritized over that of normal plane plastic work *** evaluation of plastic potential functions should not only consider the prediction accuracy of the normal plane di-rections of plastic strain rate,but also further check the diagonal plane directions of plastic strain *** mechanical properties as a function of equivalent plastic strain to calibrate parameters of the yield criterion allows the continuous capture of anisot

关键词： Proportional loading paths Diagonal plane Asymmetric yield criterion Non-associated flow rule Anisotropic hardening Sheet metal forming

Effect of Y and Ce Micro-alloying on Microstructure and Hot Tearing of As-Cast Al-Cu-Mg Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 939-952页

作者： Chunyu Yue Bowen Zheng Ming Su Yuxiang Wang Xiaojiao Zuo Yinxiao Wang xiaoguang yuan School of Materials Science and Engineering Shenyang University of TechnologyShenyang110870China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

In this work,the Al-Cu-Mg alloy with different Y(0-0.2 wt%)and Ce(0.5-1.5 wt%)are *** effect of mixed addition of Y and Ce on the grain structure and hot tearing for Al-4.4Cu-1.5Mg-0.15Zr alloy was investigated using"cross"hot tearing *** results indicate that as rare earth Y and Ce increases,the grain size becomes finer,the grain morphology changes from dendrite to equiaxed grain,and effectively reduce the hot tearing sensitivity coefficient(HTS1)and crack susceptibility coefficient(CSC)of the *** the increase of Ce element(0.5-1.5 wt%),the hot tearing susceptibility of the alloy decreases first and then *** the increase of Y element(0-0.2 wt%),the hot tearing sensitivity of the alloy *** the content of rare earth is 0.2 wt%Y+1.0 wt%Ce,the minimum HTS1 value and CSC value of the alloy are 68 and 0.53,*** earth Ce refines the alloy microstructure,shortens the feeding channel,and reduces the hot tearing ***,the rare earth Y can form Al6Cu6Y phase at the grain boundary,improve the feeding capacity of the ***,appropriate addition of rare earth Y and Ce can effectively reduce the hot tearing tendency of the alloy.

关键词： Al-Cu-Mg alloy Y and Ce Microstructure Thermal analysis Hot tearing sensitivity

DECISION FUSION FOR WIRELESS SENSOR NETWORKS UNDER NAKAGAMI FADING CHANNELS

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Journal of Electronics(China) 2010年第2期27卷 177-182页

作者： yuan xiaoguang Yang Wanhai Shi Lin School of Electronic Engineering Xidian University Xi＇an 710071 China

Decision fusion rules for Wireless Sensor Networks (WSNs) under Nakagami fading channels are investigated in this paper. Considering the application limitation of Likelihood Ratio Test fusion rule based on information of Channel Statistics using Series expansion (LRT-CSS),and the detection performance limitation of the Censoring based Mixed Fusion rule (CMF),a new LRT fusion rule based on information of channel statistics has been presented using Laplace approximation (LRT-CSL). Theoretical analysis and simulations show that the proposed fusion rule provides better detection performance than the Censoring based Mixed Fusion (CMF) and LRT-CSS fusion rules. Furthermore,compared with LRT-CSS fusion rule,the proposed fusion rule expands the application range of likelihood ratio test fusion rule.

关键词： Nakagami fading channels Wireless Sensor Network (WSN) Decision fusion