2021 Fiscal Year Final Research Report

Modeling of solidification dynamics supported by 3D time-resolved in-situ observations

Research Project

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Project/Area Number	17H06155
Research Category	Grant-in-Aid for Scientific Research (S)
Allocation Type	Single-year Grants
Research Field	Metal making/Resorce production engineering
Research Institution	Kyoto University
Principal Investigator	Yasuda Hideyuki 京都大学, 工学研究科, 教授 (60239762)
Co-Investigator(Kenkyū-buntansha)	吉矢真人大阪大学, 工学研究科, 教授 (00399601) 森下浩平九州大学, 工学研究院, 准教授 (00511875) 鳴海大翔京都大学, 工学研究科, 助教 (20827448) 勝部涼司京都大学, 工学研究科, 助教 (10839947) 柳楽知也大阪大学, 接合科学研究所, 准教授 (00379124)
Project Period (FY)	2017-05-31 – 2022-03-31
Keywords	融体・凝固 / 鋳造 / 結晶育成・成長 / 放射光 / トモグラフィー
Outline of Final Research Achievements	It has been required to understand solidification phenomena in metallic alloys based on direct observation. However, there were still limitations to the direct observations. In this study, time-resolved computed tomography (4D-CT), which uses the synchrotron radiation X-rays, and a thermodynamic-based reconstruction procedure, was developed to observe microstructure evolution during dendritic solidification in Sn, Al, Ni and Fe alloys. The developed technique allowed us to perform the two-dimensional and the three-dimensional observations. An alternative solidification and transformation mode was found in steel solidification, and the transformation significantly influenced the microstructure evolution of austenite grains. In addition, the formation mechanism of graphite nodules in cast iron, and the deformation mechanism of semisolid during solidification were studied using the developed technique.
Free Research Field	金属生産工学
Academic Significance and Societal Importance of the Research Achievements	世界において代表的な放射光施設であるSPring-8の高輝度・高平行度の単色X線を利用したコンピュータ断層撮影（CT）により、鉄鋼材料、アルミ合金などの金属材料が液相から固体に変態する過程において時々刻々と変化する凝固組織の三次元観察を実現した。観察に基づく実証的研究により鉄鋼材料などの凝固組織の形成過程やアルミ合金の凝固過程での変形機構が明らかになり、凝固ダイナミクスの新たな学理の構築に結びついた。例えば、鉄鋼材料では従来考えられてきた凝固・変態と違う形態を見出し、組織制御などに応用できる可能性を見出した。これらの知見は金属材料の製造プロセスの発展に寄与する。