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Influence of processing temperature on microstructure and microhardness of copper subjected to high-pressure torsion

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Science China(Technological Sciences) 2010年第6期53卷 1534-1539页

作者： XIE ZiLing1,2,XIE JiJia2,hong youshi2 & WU XiaoLei2 1 College of Architecture and Civil Engineering,University of Wenzhou,Wenzhou 325035,China 2 State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China College of Architecture and Civil Engineering University of Wenzhou Wenzhou China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing China

Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT),*** effects of temperature on grain refinement and microhardness variation were *** the samples after HPT processing at RT,the grain size reduced from 43 μm to 265 nm,and the Vickers microhardness increased from HV52 to ***,for the samples after HPT processing at LNT,the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery *** observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample,but further deformation induced an inhomogeneous distribution of grain sizes,with submicrometer-sized grains embedded inside micrometer-sized *** submicrometer-sized grains with high dislocation density indicated their nonequilibrium *** the contrary,the micrometer-sized grains were nearly free of dislocation,without obvious deformation trace remaining in *** images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.

关键词： copper high pressure torsion (HPT) microstructure grain size microhardness cryogenic temperature

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高压扭转铜试样的微观组织与压缩性能

金属学报 2008年第7期44卷 803-809页

作者：谢子令武晓雷谢季佳洪友士中国科学院力学研究所非线性力学国家重点实验室北京100190

通过高压扭转对铜试样施加不同程度的变形,研究了样品扭转面(ND面)和纵截面(TD面)上微观组织特征.对ND面,在较小的剪应变下,原始晶粒形貌模糊,晶粒内部形成等轴状的位错胞及亚晶结构;随变形量的增大,亚晶间取向差及亚晶内部的位错密度增... 详细信息

通过高压扭转对铜试样施加不同程度的变形,研究了样品扭转面(ND面)和纵截面(TD面)上微观组织特征.对ND面,在较小的剪应变下,原始晶粒形貌模糊,晶粒内部形成等轴状的位错胞及亚晶结构;随变形量的增大,亚晶间取向差及亚晶内部的位错密度增大,最后形成亚微米尺度的等轴晶粒.对TD面,变形初期原始晶粒被拉长,晶粒内部为位错墙分割成的层状结构,层内为拉长的位错胞;随变形程度的增大,拉长晶粒的宽度减小,与剪切方向的夹角减小,晶内层状组织间距减小,并逐渐演化成拉长的亚晶组织;进一步增大变形,晶粒拉长痕迹消失,变形组织与ND面相似,为等轴状亚微米晶粒.压缩实验表明,经16圈扭转后,整个试样上的压缩性能基本均匀,σ_(0.2)达到385 MPa,应变率敏感性指数增大至0.021.

关键词：铜高压扭转微观结构晶粒演变压缩性能

APPLICATION OF ENTHAIPY METHOD FOR MOVING BOUNDARY PROBLEM IN LASER SURFACE MELTING

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Acta Mechanica Solida Sinica 1999年第3期12卷 198-205页

作者： Wang Huicai hong youshi (Laboratory for Nonlinear Mechanics of Continuous Media,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100080,China)

A numerical analysis was carried out to study the moving boundary problem in the physical process of pulsed Nd-YAG laser surface melting prior to *** enthalpy method was applied to solve this two-phase axisymmetrical mehing *** results of tempera ture fields were obtained,which provide useful information to practical lair treatment processing. The validity of enthalpy method in solving such problems is presented.

关键词： enthalpy method puled Nd-YAG laser Stefan problem temperature field latent heat of fusion

INITIATION AND PROPAGATION OF SHORT FATIGUE CRACKS IN A WELD METAL

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INITIATION AND PROPAGATION OF SHORT FATIGUE CRACKS IN A WELD...

作者： hong youshi, LU YONGHUA and ZHENG ZHEMIN (C. M. CHENG) Institute of Mechanics, Academia Sinica, Beijing, China

Fatigue tests were performed using a purpose designed triangular shaped specimen to investigate the initiation and propagation of short fatigue cracks in a weld metal. It was observed that short fatigue cracks evolved from slip bands and were predominantly within ferrite grains. As the test progressed, the short crack density increased with minor changes in crack length. The growth of short cracks, in the early stage resulted mainly from coalescence with other existing cracks. The mechanism of short crack behaviour is discussed.

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郑哲敏先生学术成长之路初探

力学与实践 2022年第4期44卷 978-985页

作者：丁雁生金和李和娣洪友士中国科学院力学研究所北京100190

2012年度国家最高科学技术奖获奖者郑哲敏先生,于2021年8月25日病逝,享年97岁。我们曾在先生指导下学习和工作,并受先生委托承担采集先生的学术成长资料的任务。在先生逝世周年之际,我们撰文缅怀先生,尝试探讨先生学术成长之路,期待为... 详细信息

2012年度国家最高科学技术奖获奖者郑哲敏先生,于2021年8月25日病逝,享年97岁。我们曾在先生指导下学习和工作,并受先生委托承担采集先生的学术成长资料的任务。在先生逝世周年之际,我们撰文缅怀先生,尝试探讨先生学术成长之路,期待为弘扬先生的科学精神尽一份力。

关键词：成长之路国家最高科学技术奖郑哲敏学术成长缅怀先生获奖者

Orientation preference and fractal character of short fatigue cracks in a weld metal

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Orientation preference and fractal character of short fatigu...

作者： youshi hong, YONGHUA LU, ZHEMIN ZHENG Institute of Mechanics, Academia Sinica, Beijing 100080, People’s Republic of China

Short fatigue crack behaviour in a weld metal has been further investigated. The Schmid factor and the fractal dimension of short cracks on iso-stress specimens subjected to reversed bending have been determined and then applied to account for the distribution and orientation characteristics of short fatigue cracks. The result indicates that the orientation preference of short cracks is attributed to the large values of Schmid factor at relevant *** Schmid factors of most slip systems, which produced short cracks, are less than or equal to 0.4. Crack length measurements reveal that short crack path, compared to that of long crack, possesses a more stable and relatively larger value of fractal dimension. This is regarded as one of the typical features of short cracks.

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试样疲劳性能尺度效应的概率控制体积方法

力学学报 2019年第5期51卷 1363-1371页

作者：李亚波宋清源杨凯陈一萍孙成奇洪友士中车青岛四方机车车辆股份有限公司工程实验室山东青岛266111 中国科学院力学研究所非线性力学国家重点实验室北京100190 中国科学院大学工程科学学院北京100049

试样尺度、缺口和加载方式通常对材料的疲劳性能具有重要影响.因此,发展关联试样尺度、缺口和加载方式对疲劳强度影响的方法对于从材料疲劳性能到结构件疲劳性能的预测具有重要意义.首先,采用旋转弯曲加载和轴向加载方式对不同几何形状E... 详细信息

试样尺度、缺口和加载方式通常对材料的疲劳性能具有重要影响.因此,发展关联试样尺度、缺口和加载方式对疲劳强度影响的方法对于从材料疲劳性能到结构件疲劳性能的预测具有重要意义.首先,采用旋转弯曲加载和轴向加载方式对不同几何形状EA4T车轴钢试样进行了疲劳实验.实验结果表明,由于试样尺度的增加,轴向加载下狗骨形试样的疲劳强度明显低于沙漏形试样;相同寿命下,缺口显著降低试样的疲劳强度.疲劳断口扫描电镜观测结果表明,疲劳裂纹均起源于试样表面.沙漏形试样和狗骨形试样疲劳断口大多只有一个裂纹源,而缺口试样疲劳断口均具有多裂纹源特征.然后,采用概率控制体积方法研究了试样尺度、缺口和加载方式对疲劳强度的影响,并与临界距离和应变能密度方法进行了比较.结果表明,概率控制体积方法能够更好地关联试样尺度、缺口和加载方式对EA4T车轴钢疲劳强度的影响.最后,提出一种基于控制体积的结构件疲劳强度预测方法,并用于具有不连续高应力区域车轴钢试样的疲劳强度预测,预测结果与实验结果吻合.

关键词： EA4T车轴钢尺度效应缺口效应加载方式疲劳强度控制体积方法

Acousto-optic scanning multi-photon lithography with high printing rate

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Opto-Electronic Advances 2024年第2期7卷 1-3页

作者： Minghui hong Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China

As a manufacturing method that is focused on end-users,3D printing has gained a lot of attention in recent years due to its unique advantages in fabricating complex three-dimensional *** new micro-nano 3D printing methods have been developed to meet the demand for high-precision and high-yield *** them,multi-photon-photon lithography(MPL) is a promising 3D nanofabrication technology due to its capability of true 3D digital processing and nanoscale processing resolution beyond the diffraction *** has been widely used to fabricate microoptics10,11,photonic crystals12,microfluidics13,meta-surfaces14,and mechanical metamaterials15.

关键词： photon Acous scanning

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激光熔覆铁基大厚度非晶合金表层的研究

材料热处理学报 2001年第1期22卷 51-54页

作者：武晓雷洪友士中科院力学研究所非线性力学国家重点实验室北京100080

利用激光熔覆制备了大厚度铁基非晶合金表层 ,非晶层厚度为 0 74mm ,表征非晶合金过冷液相区的ΔT(非晶转变温度及晶化温度之差 )为 6 7K。XRD、TEM与DSC分析表明表层为单相非晶。

关键词：大厚度非晶表层激光熔覆铁基非晶合金