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Thermodynamics properties and thermal conductivity of Mg_2Pb at high pressure

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Science China(Physics,Mechanics & Astronomy) 2013年第10期56卷 1854-1860页

作者： duan yonghua SUN Yong Faculty of Material Science and Technology Kunming University of Science and Technology Key Lab of Advanced Materials of Yunnan Province Kunming University of Science and Technology

The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by *** enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the experiments and other theoretical *** thermal conductivity and coefficient of thermal expansion of Mg2 Pb at high pressure were *** thermal conductivity presents a second-order polynomial with *** calculated thermal conductivity of Mg2Pb indicates that it is suitable to be used as thermal conductor at 0 K.

关键词： thermodynamics properties thermal conductivity first-principles Mg2Pb

Tuning the growth of intermetallic compounds at Sn-0.7Cu solder/Cu substrate interface by adding small amounts of indium

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Journal of Materials Science & Technology 2024年第15期182卷 246-259页

作者： Ancang Yang Yaoping Lu yonghua duan Mengnie Li Shanju Zheng Mingjun Peng Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093China College of Physics and Information Engineering Fuzhou UniversityFuzhou 350108China

The void defect in intermetallic compounds(IMCs)layer at the joints caused by inhomogeneous atomic diffusion is one of the most important factors limiting the further development of Sn-based *** this work,the thermodynamic stability of IMCs(high-temperatureη-Cu_(6)Sn_(5)and o-Cu_(3)Sn phases)was improved by adding small amounts of indium(In),and the IMCs layers with moderate thickness,low defect concentrations and stable interface bonding were successfully *** formation order of compounds and the interfacial orientation relationships in IMCs layers,the atomic diffusion mechanism,and the growth tuning mechanism of In onη-Cu_(6)Sn_(5)and Cu_(3)Sn,after In adding,were discussed com-prehensively by combining calculations and *** is the first time that the classic heteroge-neous nucleation theory and CALPHAD data were used to obtain the critical nucleus radius ofη-Cu_(6)Sn_(5)and Cu_(3)Sn,and to explain in detail the main factors affecting the formation order and location of IMCs at joints during the welding process.A novel and systematic growth model about IMCs layers in the case of doping with alloying elements was *** growth tuning mechanism of In doping onη-Cu_(6)Sn_(5)and Cu_(3)Sn was further clarified based on the proposed model using first-principles *** growth model used in this study can provide insights into the development and design of multiele-ment Sn-based solders.

关键词： Sn-0.7Cu solder IMCs Aging Atomic migration barrier Growth tuning

First-Principles Calculations on Electronic Structure, Adhesion Strength, and Interfacial Stability of Mg(0001)/AlB_(2)(0001) Nucleation Interface

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Acta Metallurgica Sinica(English Letters) 2024年第10期37卷 1752-1766页

作者： Bo Li yonghua duan Mengnie Li Lishi Ma Shanju Zheng Mingjun Peng Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming650093China

In this work,Mg(0001)/AlB_(2)(0001)interfaces with various terminations and stacking orders were constructed,and the atomic and electronic structures and adhesion work(Wad)of the interface were investigated using the first-principles ***,during the geometry optimization process,the B-mid-top(B-MT)Mg(0001)/AlB_(2)(0001)interface exhibits the most significant interface changes and manifests the least *** movement of Mg atoms in the first layer of the Mg surface slab,along the normal direction,results in a structure akin to the structurally optimized hexagonal close-packed(HCP)*** B-HCP interface demonstrates the highest stability,the largest ideal Wad,and the smallest interface *** interface enhances the binding strength of the Mg-side sub-interface,but diminishes the binding strength of the AlB_(2)-side ***,Mg atoms can form metallic/covalent mixed bonds with Al atoms on the Al-terminal AlB_(2) surface and form ionic bonds with B atoms on the B-terminal AlB_(2) ***(0001)/AlB_(2)(0001)interface has good bonding *** research provides strong theoretical support for an in-depth understanding of Mg/AlB_(2) interface characteristics.

关键词： Mg AlB2 First-principles Interface Adhesion strength Surface energy

Constructing the coherent transition interface structure for enhancing strength and ductility of hexagonal boron nitride nanosheets/Al composites

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Journal of Materials Science & Technology 2023年第14期145卷 235-248页

作者： Lishi Ma Xiang Zhang yonghua duan Siyuan Guo Dongdong Zhao Chunnian He Naiqin Zhao School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin 300072China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207China School of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China Key Laboratory of Advanced Ceramics and Machining Technology Ministry of EducationTianjin UniversityTianjin 300072China

The deformation incompatibility of components is a bottleneck restricting the exaltation of the strength and ductility of ***,the coherent transition interface was designed and produced in hexagonal boron nitride nanosheets(BNNSs)/Al composites by reaction sintering route,expecting to re-lieve the deformation incompatibility between BNNSs and *** is demonstrated that with the sintering temperature for composites raising from 600℃ to 650℃,700℃ and 750℃,different interface bonding characteristics,which involve nucleation and growth of AlN continuous nanolayer,were ***-thermore,first-principles calculations show that the generation of the coherent transition interface im-proved the interfacial bonding strength of BNNSs/Al composites through covalent *** composites with coherent transition interface exhibit excellent strength-toughness combination in tensile and impact *** finite element simulation and in-situ approach under tensile tests were applied to investigate the influence of transition interface structure on deformation behavior of BNNSs/Al *** is found that the generation of the transition interface can not only weaken the stress partitioning behavior in the elastic stage,but also constrain the crack initiation and propagation behavior in the elastic-plastic stage and plastic stage,thereby improving the deformation compatibility between BNNSs and *** present work provides a novel view into the breakthrough for the trade-offrelationship of strength and ductility by coherent transition interface design in nanocomposites.

关键词： Nanocomposites Al-BNNSs system In-situ interface reaction Coherent transition interface Strength and ductility

(α,β,γ)-Nb_5Si_3相的稳定性、弹性常数和热力学性质(英文)

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稀有金属材料与工程 2015年第1期44卷 18-23页

作者：段永华昆明理工大学云南省新材料制备与加工重点实验室云南昆明650093

采用第一性原理计算了金属间化合物α-Nb5Si3,β-Nb5Si3和γ-Nb5Si3的结构稳定性、弹性常数、热力学性质和电子结构,并利用Voigt-Reuss-Hill方法计算了弹性常数。结构参数优化结果与实验值基本一致;结合能和形成焓结果表明α-Nb5Si3的... 详细信息

采用第一性原理计算了金属间化合物α-Nb5Si3,β-Nb5Si3和γ-Nb5Si3的结构稳定性、弹性常数、热力学性质和电子结构,并利用Voigt-Reuss-Hill方法计算了弹性常数。结构参数优化结果与实验值基本一致;结合能和形成焓结果表明α-Nb5Si3的结构稳定性最好。最后分析和讨论了3种不同Nb5Si3相的延展性和弹性各向异性。

关键词： Nb5Si3 第一性原理弹性常数热容

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高二氧化碳浓度下石灰石的热分解反应动力学

硅酸盐学报 2013年第5期41卷 637-643页

作者：李辉张乐乐段永华闵永刚西安建筑科技大学材料与矿资学院陕西循环经济工程技术院西安710055

用热重分析仪,在升温速率5～20K/min范围内,研究CO2浓度对石灰石热分解反应动力学参数的影响及高CO2浓度气氛下两种化学成分与矿物组成不同的石灰石的热分解反应动力学。采用改进的双外推法计算这两种石灰石的热分解反应动力学参数。结... 详细信息

用热重分析仪,在升温速率5～20K/min范围内,研究CO2浓度对石灰石热分解反应动力学参数的影响及高CO2浓度气氛下两种化学成分与矿物组成不同的石灰石的热分解反应动力学。采用改进的双外推法计算这两种石灰石的热分解反应动力学参数。结果表明:石灰石热分解反应的活化能与气氛中的CO2浓度呈指数增加关系;在高CO2浓度气氛条件下石灰石的热分解过程机理模型为随机成核和随后生长模型,得到了反应机理函数,CO2浓度不同,反应级数不同,反应级数的变化范围为2/5～2/3;CO2浓度越高,石灰石热分解的活化能越高,反应级数越大;在相同CO2浓度气氛条件下,石灰石中含有一定量白云石有助于其分解反应的进行。

关键词：高二氧化碳浓度石灰石分解动力学改进的双外推法热重分析

B对铸造Pb-Mg-10Al合金摩擦磨损性能的影响

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特种铸造及有色合金 2011年第9期31卷 800-803页

作者：段永华孙勇何建洪昆明理工大学材料科学与工程学院云南省新材料制备与加工重点实验室

利用立式高频感应炉制备出3组不同B含量的铸造Pb-Mg-10Al合金,并对其摩擦磨损性能进行了研究。采用X射线衍射仪分析物相,用扫描电镜观察其显微组织。结果表明,随着B的添加,合金组织中出现了陶瓷相AlB2颗粒,由于陶瓷相的增多,合金的硬度... 详细信息

利用立式高频感应炉制备出3组不同B含量的铸造Pb-Mg-10Al合金,并对其摩擦磨损性能进行了研究。采用X射线衍射仪分析物相,用扫描电镜观察其显微组织。结果表明,随着B的添加,合金组织中出现了陶瓷相AlB2颗粒,由于陶瓷相的增多,合金的硬度得到显著提高。室温滑动摩擦磨损试验表明,合金的耐磨性能随B含量的增加而增加,当B含量为2%时,其磨损量和摩擦因数最小。

关键词： Pb-Mg-10Al合金 B 陶瓷相摩擦磨损摩擦因数

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基于网络环境下的体育教学模式探讨

黔西南民族师范高等专科学校学报 2005年第1期 65-67页

作者：段永华黔西南民族师范高等专科学校体育系贵州兴义562400

在当前体育教学改革发展时期,利用网络教学所具有的各种优势加快体育教学的改革步伐,创设基于网络环境下的体育教学模式,不断提高体育教学水平。

关键词：网络环境体育教学模式教学目标

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Al对Pb-Mg合金组织与力学性能的影响

材料导报 2009年第24期23卷 47-49页

作者：段永华孙勇彭明军昆明理工大学云南省新材料制备与加工重点实验室昆明650093

通过扫描电子显微镜、X射线衍射仪和力学性能测试研究了Al对Pb-Mg合金组织与力学性能的影响。结果表明,添加5%～10%的Al后,合金组织中出现了胞状Mg+Mg_(17)Al_(12)相,对其它组织的生长起到了关键的制约作用,合金的显微组织得到细化,且A... 详细信息

通过扫描电子显微镜、X射线衍射仪和力学性能测试研究了Al对Pb-Mg合金组织与力学性能的影响。结果表明,添加5%～10%的Al后,合金组织中出现了胞状Mg+Mg_(17)Al_(12)相,对其它组织的生长起到了关键的制约作用,合金的显微组织得到细化,且Al含量越高,合金组织越细;随Al含量的增加,合金的硬度与抗拉强度也提高,Al含量为10%时合金的硬度与抗拉强度分别达到156HB和300MPa。

关键词： Pb-Mg合金细化显微组织抗拉强度硬度