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Fabrication of Bulk β-FeSi_2 Crystal With ThreeDimensional Alignment by an Oscillating Magnetic Field

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Journal of Iron and Steel Research(International) 2012年第S1期19卷 183-186页

作者： Noriaki Nakatsuka Keiji Kurokawa tomoya nagira Masato Yoshiya Hideyuki Yasuda Department of Adaptive Machine Systems Osaka UniversityOsaka 565-0871Japan

It has been reported that an anisotropic magnetic field could produce the three-dimensional alignment of fine single-crystal particles with the orthorhombic crystal ***,the three-dimensional alignment was achieved only in *** of bulk 'single' materials that have the three-dimensional alignment of grains has been *** study proposes a procedure for the fabrication,which consists of slip casting under an oscillating magnetic field and *** of casting and sintering conditions achieved the three-dimensionally aligned bulk β-FeSi_2.

关键词： pseudo single crystal crystallographic orientation magnetic alignment

Direct Observation of Thermoelectric Magnetic Convection in Unidirectionally Solidified Al-Cu Alloys

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Journal of Iron and Steel Research(International) 2012年第S1期19卷 34-39页

作者： Hideyuki Yasuda Keisuke Inoue Yudai Minami tomoya nagira Masato Yoshiya Kentaro Uesugi Keiji Umetani Department of Adaptive Machine Systems Osaka UniversityOsaka 565-0871Japan Japan Synchrotron Research Institute/SPring-8 Hyogo 679-5198Japan

This study performed the time-resolved and in-situ observation of unidirectional solidification of A1-Cu and Sn-Bi alloys under a static magnetic field up to 0.45 *** the case of Sn-Bi alloy,the static magnetic field reduced the local convection around the primary dendrite *** thermoelectric convection was *** the other hand,the thermoelectric convection was clearly observed in Al-Cu *** observed convection was consistently explained by the thermoelectric magnetic *** to a simplified model,the thermoelectric magnetic convection can be induced if the difference in the thermoelectric power between the solid and the liquid phases is in the order of 1 μV/K and temperature gradient is several K/mm.

关键词： static magnetic field natural convection thermoelectric effect dendrite

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钢的枝晶生长及相关现象的观测

钢的枝晶生长及相关现象的观测

Evaluation of dynamic development of grain structure during friction stir welding of pure copper using a quasi in situ method

作者： Hideyuki Yasuda tomoya nagira Masato Yoshiya Akira Sugiyama Kentaro Uesugi Keiji Umetani 大阪大学机械系统系大阪大学先进结构与功能材料设计中心大阪产业大学企业家策划系

用同步X射线可以对钢的凝固过程进行原位观测,铁硅合金和铁碳合金中的枝晶形成过程清晰可见。对于铁硅合金,液相中硅的浓度可以从试样中X射线的透射强度估计出来。对传统的O.45mass%C碳钢,可以观测从6相向γ相的转变过程。时间分辨图像... 详细信息

用同步X射线可以对钢的凝固过程进行原位观测,铁硅合金和铁碳合金中的枝晶形成过程清晰可见。对于铁硅合金,液相中硅的浓度可以从试样中X射线的透射强度估计出来。对传统的O.45mass%C碳钢,可以观测从6相向γ相的转变过程。时间分辨图像显示,这种转变与包晶的转变/反应大不相同。X射线成像技术有望成为理解高温下凝固现象的一种工具。

关键词：实时观测偏析现象晶粒选择同步辐射

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Journal of Materials Science & Technology 2019年第7期35卷 1412-1421页

作者： X.C.Liu Y.F.Sun T.nagira K.Ushioda H.Fujii Joining and Welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka567-0047Japan School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an710072China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China

By employing a quasi in situ method, we investigated the dynamic evolution of the grain structure con-sidering the material flow, strain, and strain rate in the friction stir welding of pure copper. The tool' stop action' and rapid cooling were employed and a brass foil was used as a marker to show the material flow path. The grain structure along the material flow path was characterised using electron backscatter diffraction. Static recrystallization occurs for the work-hardened base material in the preheating stage in front of the tool In the acceleration flow stage, grains are significantly refined by plastic deforma-tion, discontinuous dynamic recrystallization, annealing twinning during the strain-induced boundary migration and slight continuous dynamic recrystallization. In the deceleration flow stage, due to a strain reversal, the grain first coarsens, and is thereafter refined again. Finally, the hot-deformed material in the shoulder-affected zone is ‘frozen’ directly whereas that in the probe-affected zone undergoes signif-icant annealing;thus, the recrystallized microstructure and 45°-rotated cube texture are obtained in the probe-affected zone.

关键词： Friction stir welding Grain structure Material flow Pure copper EBSD