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Coercivity mechanism of high-performance anisotropic heterostructure SmCo5 magnets

Journal of Rare Earths 2024年第10期42卷 1882-1888页

作者： Yuan Teng Yuqing Li Weiqiang Liu xiaochang xu Zhanjia Wang Jianjun Yang Dongtao Zhang Hongguo Zhang Qingmei Lu Qiong Wu Weixing Xia Ming Yue Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of Technology School of Mechanical and Electrical Engineering Henan Institute of Science and Technology School of Mechanical Engineering Anyang Institute of Technology Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of Sciences

Due to its large magnetocrystalline anisotropy field and high Curie temperature,SmCo-based magnets are irreplaceable in high-temperature applications,The hot-deformed SmCo-based magnets are especially attractive for their excellent corrosion resistance,making them more suitable for harsh ***,it is still challenging for hot-deformed SmCo-based magnets to obtain high magnetization and high coercivity ***,it is necessary to analyze the relationship between its microstructure and magnetic properties and explore its magnetic hardening mechanism to guide the further improvement of magnetic *** this paper,the anisotropic heterostructure SmCo5magnet was prepared by combining large height-reduction and introducing a nano-grained Smrich *** c-axis texture,（BH）m of 16.1 MGOe,and Hciof 9.6 kOe were obtained via the heterostructure with SmCo5micron-grain and Sm-rich nano-scale *** magnetic domain observation and technical magnetization analysis demonstrate that the coe rcivity mechanism is dominated by *** results also show that the smooth and Sm-rich precipitated grain boundary provides weak pinning *** provides a reference for the development of high-pe rformance nanocrystalline SmCo5magnets.

关键词： Coercivity mechanism Heterostructure Hot-deformed SmCo magnet Permanent magnet Rare earths

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Effect of heterogeneous microstructure on magnetization reversal mechanism of hot-deformed Nd-Fe-B magnets

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Journal of Rare Earths 2019年第10期37卷 1088-1095页

作者： Yuqing Li xiaochang xu Ming Yue Dan Wu Weiqiang Liu Dongtao Zhang Key Laboratory of Advanced Functional Materials Ministry of Education of China College of Materials Science and Engineering Beijing University of Technology

The hot-deformed(HD) Nd-Fe-B magnets show heterogeneous microstructure composed of coarse and fine grain regions. It is significant to fully understand the influence of this complex microstructure on the magnetization reversal process which can give the guidance for the enhancement of the magnetic properties. In this paper, the heterogeneous microstructure of the(HD) Nd-Fe-B magnets were characterized from the morphology, size, macro-texture and micro-structure. In addition, the magnetization reversal process of the HD Nd-Fe-B magnets was systematically analyzed by magnetic measurement, insitu domain evolution observation and micromagnetic simulation. The results indicate that the HD NdFe-B magnets mainly consist of fine grain regions(FGRs) and coarse grain regions(CGRs). The FGRs show plate-like grains with fine grain size and strong c-axis texture, while the CGRs show equiaxial grains with large grain size and weak c-axis texture. In particular, it is worth noting that the texture in homogeneity exists not only between FGRs and CGRs, but also inside both the FGRs and CGRs. The dominant coercivity mechanism of the HD Nd-Fe-B magnets is domain wall pinning. Also, the experimental analysis shows that the reverse domain is formed and expanded in the CGRs at low reverse applied field, while the reverse domain occurs in the FGRs at higher reverse applied field. The micromagnetic simulation results also confirm the above magnetization reversal process. In addition, micromagnetic simulation results also show that the orientation of the grains also affects the pinning strength, besides the grain size.

关键词： Hot-deformed Nd-Fe-B magnet Heterogeneous microstructure Magnetization reversal Coercivity mechanism Rare earths

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Morphology and magnetic properties of Sm_(2)Co_(7)/α-Fe nanocomposite magnets produced by high energy ball milling and spark plasma sintering

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Journal of Rare Earths 2021年第3期39卷 312-316,I0003页

作者： Yitong Zhuge Yuqing Li xiaochang xu Dongtao Zhang Hongguo Zhang Weiqiang Liu Ming Yue Key Laboratory of Advanced Functional Materials Ministry of Education of ChinaCollege of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124China

In this article,the Sm_(2)Co_(7)/α-Fe nanocomposite magnets were prepared by high energy ball milling and spark plasma sintering *** effect of soft phase content on the magnetic properties was *** to 30 wt% α-Fe was added into Sm_(2)Co_(7) matrix without the decrease of *** energy product(BH)max of 9.2 MGOe was obtained with 20 wt% α-*** observation shows that the grain size of α-Fe is 20-50 nm which ensures a good coupling effect between soft and hard *** more thing needs to be mentioned is that there exists inter-diffusion between Sm-Co phase and α-Fe ***,our results can also illustrate that the Sm_(2)Co_(7)/α-Fe nanocomposite magnets are able to acquire better magnetic properties than the SmCo_(5)/α-Fe magnets prepared by the same process due to the large domain width of Sm_(2)Co_(7) phase.

关键词： Nanocomposite magnet Microstructure Interdiffusion Exchange coupling effect Spark plasma sintering Rare earths

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07MnNiMoDR钢热轧变形本构方程及轧制力预测

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锻压技术 2024年第2期49卷 172-181页

作者：汪后明张计谋王振陈旭鹏石润坤许晓嫦湖南华菱湘潭钢铁有限公司湖南湘潭411101 中南大学材料科学与工程学院湖南长沙410083

轧制力的预测是热轧工艺能够顺利进行的重要前提步骤。为预测热轧过程中轧制力的大小,采用热模拟试验机对07MnNiMoDR钢进行了单道次热压缩实验,获得了温度为850~1150℃、应变速率为0.1~10 s^(-1)、真应变为0.9条件下的高温流变行为,分... 详细信息

轧制力的预测是热轧工艺能够顺利进行的重要前提步骤。为预测热轧过程中轧制力的大小,采用热模拟试验机对07MnNiMoDR钢进行了单道次热压缩实验,获得了温度为850~1150℃、应变速率为0.1~10 s^(-1)、真应变为0.9条件下的高温流变行为,分析了不同变形条件下07MnNiMoDR钢的动态再结晶及动态回复行为,并基于Arrhenius方程及变形机理建立了其热轧本构方程。利用材料性能分析软件JMatPro计算了07MnNiMoDR钢的温度场参数;基于高温热轧本构方程及温度场参数,通过有限元分析软件Deform-3D对热轧过程进行模拟,验证了轧制力预测的准确度。结果表明:所建立的07MnNiMoDR钢的本构方程及温度参数,对预测轧制力具有良好的预测精度,R值为0.9875。

关键词： 07MnNiMoDR钢热轧变形本构方程轧制力温度场参数

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Analysis on deformation and texture formation mechanism of hot-deformed Nd-Fe-B magnets based on heterogeneous structure evolution

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Journal of Materials Science & Technology 2021年第21期80卷 28-35页

作者： Yuyang Tang Yuqing Li xiaochang xu Ming Yue Weiqiang Liu Hongguo Zhang Qingmei Lu Weixing Xia Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing100124China Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo315201China

In this paper, microstructure, micromagnetic structure, texture, together with magnetic properties of the hot-deformed(HD) Nd-Fe-B magnets were systematically studied to understand the deformation process and the formation mechanism of c-axis texture. The results show that the platelet grains are formed in the fine-grain regions at the initial stage of the deformation. As the amount of deformation increases, the proportion of platelet grains increases and arranges gradually, causing the formation of c-axis texture, till the grain merging occurres when the deformation is excessive. It should be noted that the rare earth-rich phase in the fine-grained region slowly diffuses to the coarse-grained region where only grain growth can be observed during deformation. The deformation mechanism and formation of c-axis texture in HD Nd-Fe-B magnets can be deduced to be accomplished by the processes of dissolution-precipitation diffusion, grain rotation and grain arrangement, based on the characterization of microstructure and texture evolution. Also, approaches to optimize the preparation process and magnetic properties of the hot-deformed Nd-Fe-B magnets were discussed.

关键词： Hot-deformed Nd-Fe-B magnet Heterogeneous microstructure Deformation mechanism C-axis texture Coercivity

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Microstructure evolution of hot-deformed SmCo-based nanocomposites induced by thermo-mechanical processing

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Journal of Materials Science & Technology 2023年第7期138卷 193-202页

作者： Yuan Teng Yuqing Li xiaochang xu Ming Yue Weiqiang Liu Dongtao Zhang Hongguo Zhang Qingmei Lu Weixing Xia Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo 315201China

Nanocomposite permanent magnets have ultra-high theoretical magnetic energy products,due to cou-pling of the soft/hard magnetic phases,inciting strict microstructural *** this study,the microstructure evolution,including the phase transition,morphological changes,and texture formation,of hot-deformed SmCo-based nanocomposites under thermal-stress-strain coupling was characterized to determine a possible strategy for achieving high *** SmCo_(5)/α-Fe nanocomposites precursor contained fine and dispersed Sm(Fe,Co)_(5)and Fe-Co grains and exhibited a two-stage phase transforma-tion accompanied by grain *** the early stage of deformation at relatively low temperature,the adjacent Sm(Co,Fe)5 and Fe-Co phase formed the Sm_(2)(Co,Fe)_(17)-H phase,which was stable only with small grain *** the high-temperature deformation stage,the Sm_(2)(Co,Fe)_(17)-H phase transformed into the Sm_(2)(Co,Fe)_(17)-R phase with large grain *** addition,the strong c-axis texture formed in the Sm(Co,Fe)_(5)phase but not in the Sm_(2)(Co,Fe)_(17)-R ***,the phase transition process and texture formation mechanism were systematically analyzed by transmission electron *** ini-tiation of a slip system and/or preferential grain growth explained the formation of texture under the action of uniform stress and strain and assisted by dispersed Sm-rich *** Sm_(2)(Co,Fe)_(17)-R grains with poor orientations and large grain sizes did not achieve magnetic hardening,which also dam-age the magnetic *** to the results of this work,we also presented a new strategy to prepare high-performance SmCo-based nanocomposites magnets.

关键词： Nanocomposites Phase transition Microstructure C-axis texture Hot deformation

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多路径模型对相位测量轮廓术的影响

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计算机辅助设计与图形学学报 2014年第4期26卷 566-573页

作者：许晓畅王永昌刘凯四川大学电气信息学院成都610065 KLA-Tencor MilpitasCA95035USA

为了克服多路径效应对相位测量轮廓术的影响,提出一种相位融合算法.首先建立多路径效应的数学模型,并利用该模型分析多路径效应引起的相位误差,得出了该效应引起的相位误差主要发生在反射率变化剧烈的地方,其除了与邻域内每点的真相位... 详细信息

为了克服多路径效应对相位测量轮廓术的影响,提出一种相位融合算法.首先建立多路径效应的数学模型,并利用该模型分析多路径效应引起的相位误差,得出了该效应引起的相位误差主要发生在反射率变化剧烈的地方,其除了与邻域内每点的真相位值和真反射率有关外,还与扫描的方向有关的结论;然后基于该分析推导出相位融合算法,沿X,Y方向扫描分别得到2组相位值,再根据物体表面反射率的变化对2组相位进行融合,完成相位的修正.实验结果表明,即使投射大量的编码图片,由多路径效应引入的相位误差仍然存在且不可忽略,采用文中算法可以有效地使相位误差减小2倍.

关键词：无接触式三维测量相位测量轮廓术多路径模型相位误差相位修正

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高校个性化创新创业人才培养模式研究

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国家教育行政学院学报 2015年第3期 27-31页

作者：姜慧殷惠光徐孝昶徐州工程学院江苏徐州221111

个性化创新创业人才培养模式是指以个性化教育为基本手段,以高素质创新创业人才培养为根本旨归的一种崭新的高等教育范型。国外发达国家非常重视高校创新创业教育,形成了创新创业课程模式、创新创业项目模式、高校科技园模式和导师制模... 详细信息

个性化创新创业人才培养模式是指以个性化教育为基本手段,以高素质创新创业人才培养为根本旨归的一种崭新的高等教育范型。国外发达国家非常重视高校创新创业教育,形成了创新创业课程模式、创新创业项目模式、高校科技园模式和导师制模式等卓有成效的创新创业人才培养模式。我国高校个性化创新创业人才培养必须注意树立个性化创新创业人才培养理念,构建层次多样的创新创业人才培养模式,建立基于个性化的创新创业教育体系,优化个性化的创新创业教学评价体系,完善个性化创新创业人才培养保障措施。

关键词：高校个性化教育创新创业人才培养模式

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热处理工艺对15CrMoR钢带状组织和冲击性能的影响

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金属热处理 2020年第10期45卷 124-128页

作者：刘丹陈广兴徐琛许晓嫦湖南华菱湘潭钢铁有限公司湖南湘潭411101 中南大学材料科学与工程学院湖南长沙410083

利用光学显微镜、扫描电镜和冲击试验机等仪器研究了15CrMoR钢中带状组织在热处理过程中的演变及其对冲击性能的影响。结果表明:奥氏体化后缓冷会出现铁素体-珠光体带状组织,快冷则可以抑制带状组织的出现,但快冷会导致粒状贝氏体等非... 详细信息

利用光学显微镜、扫描电镜和冲击试验机等仪器研究了15CrMoR钢中带状组织在热处理过程中的演变及其对冲击性能的影响。结果表明:奥氏体化后缓冷会出现铁素体-珠光体带状组织,快冷则可以抑制带状组织的出现,但快冷会导致粒状贝氏体等非平衡组织形成。粒状贝氏体组织中的贝氏体铁素体基体和马氏体-奥氏体岛在回火过程中逐渐沿Cr、Mo等碳化物形成元素偏聚的区域分解出碳化物,形成富碳化物带,降低钢的横向冲击性能。15CrMoR钢加热到1100℃并保温7 h后可消除带状组织,改善钢的横向冲击性能。

关键词： 15CrMoR钢带状组织冲击性能热处理

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断裂与重构:农村的“空心化”到“产业化”

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南京农业大学学报（社会科学版） 2014年第3期14卷 16-22页

作者：刘永飞徐孝昶许佳君河海大学公共管理学院江苏南京210098 连云港市委党校江苏连云港222000 徐州工程学院江苏徐州221111

农村空心化是我国传统社会向现代社会、农业社会向工业社会变迁过程中农村滞化、弱化、退化的真实写照,是一个集空间、人口、社会层面问题交织于一体的社会事实。它有其产生的内在机理,是农村社会发展与整个社会发展的断裂之症。治疗这... 详细信息

农村空心化是我国传统社会向现代社会、农业社会向工业社会变迁过程中农村滞化、弱化、退化的真实写照,是一个集空间、人口、社会层面问题交织于一体的社会事实。它有其产生的内在机理,是农村社会发展与整个社会发展的断裂之症。治疗这一断裂之症的良药便是进行"集聚效应"思维下的农村产业化集聚与发展,以实现人才、资金、技术、知识、资源集聚和回流,实现农村社会发展的重构,促进农村的和谐与发展,进而为农村的城镇化建设做好准备。

关键词：断裂重构空心化产业化集聚效应

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