Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Zhang, Y.*; 丸澤 賢人*; 工藤 航平*; 諸岡 聡; Harjo, S.; 宮本 吾郎*; 古原 忠*
ISIJ International, 64(2), p.245 - 256, 2024/01
被引用回数：2 パーセンタイル：67.89(Metallurgy & Metallurgical Engineering)As-quenched martensite in carbon steels needs to be tempered to restore its ductility and toughness for practical applications. During tempering of martensite, microstructural evolutions induced by a series of reactions relevant to carbon diffusion is known to occur. In this study, multi-aspect characterization using advanced techniques such as in-situ neutron diffraction, transmission electron microscopy and three-dimensional atom probe tomography, was performed to investigate the changes in tetragonality, physical properties, microstructure and solute carbon content in high-carbon martensite, with an aim to clarify its low-temperature tempering behaviors. A binary alloy with a chemical composition of Fe-0.78 mass%C was austenitized and quenched to prepare the as-quenched martensite, followed by tempering in continuous heating at different heating rates. It was found that various reactions occurred sequentially during tempering, starting from the structure modulation generated by carbon clustering in the 0th stage, then followed by the precipitation of metastable 
-carbide particles on linear features in the 1st stage, towards the later decomposition of retained austenite and precipitation of cementite in the 2nd and 3rd stages, respectively. After analyzing the experimental results, the solute carbon content in martensite tempered under various conditions was found to be in good agreement with that estimated from the lattice volume expansion, whereas the evaluation based on the tetragonality might lead to some underestimation of the solute carbon content in martensite tempered at high temperatures.
平塚 一; 木津 要; 市毛 尚志; 本田 正男; 岩橋 孝明*; 佐々木 昇*; 宮 直之; 細金 延幸; 小田 泰嗣*; 吉田 和人*
プラズマ・核融合学会誌, 76(11), p.1189 - 1197, 2000/11
JT-60Uでは、高密度プラズマの長時間保持を目的として、直線型加速方式、エクスツルーダー型生成方式を用いた遠心加速方式ペレット入射装置を開発した。この方式は、低温状態での重水素ガスペレット化制御、ペレットが発生するアブレーションガスの対策、射出方向の安定化、衝突対策等が重要である。そのため、ペレット生成中の観察が行えるようにしたうえで、固体燃料供給管等の冷却強化、排気口の設置による発生ガスの排気、遠心加速部分からの飛び出し防止及び飛行過程での衝突破損防止等の工夫・開発を行った。その結果、固い透明な重水素の氷の生成を観察でき、2.1mmの立方体(キュービック)のペレットを的確に切断・装填し、加速・射出することができた。以上により、ペレット射出速度410m/sにおいて、周波数5Hzで7s間、周波数10Hzで3.5s間の連続射出に成功した。本論文は、装置の原理、構造、試験結果等について報告する。
吉田 勝; 熊倉 稔; 嘉悦 勲
J.Pharm.Sci., 68(7), p.860 - 862, 1979/00
被引用回数：13ジメチルアミノエーテルメタアクリレートーメタアクリル酸コポリマーは陽イオン型ポリマーで胃液pHにおいてのみ溶解し、メチルメタアクリルレートーメタアクリル酸コポリマーは、陰イオン型ポリマーで腸液pHにおいてのみ溶解する。これらのコポリマー存在下、ヒドロキシエチルメタアクリレートのようなガラス化性モノマーでかつ、生体親和性の大きいモノマーを低温下で放射線重合することにより、アスピリンなどの医薬品を含むカプセルを調製した。このカプセルからの医薬品の溶出性をpH2~10の範囲で検討した。また、多孔質構造と溶出性の関係は走査電子顕微鏡を用いて検討し、pHに依存しないポリエチレングリコール#600存在下での多孔質構造、溶出性との関係についても比較検討した。
高村 三郎; 前田 裕司; 奥田 重雄
Journal of the Physical Society of Japan, 26(5), p.1120 - 1124, 1969/00
抄録なし
高村 三郎; 前田 裕司; 奥田 重雄
Journal of the Physical Society of Japan, 25(2), p.418 - 420, 1968/00
被引用回数：2抄録なし
Zhang, Y.*; 丸澤 賢人*; 工藤 航平*; 諸岡 聡; 宮本 吾郎*; 古原 忠*
no journal, ,
As-quenched martensite in carbon steels needs to be tempered to restore its ductility and toughness for practical applications. During tempering, a series of reactions relevant to carbon diffusion are known to occur sequentially, causing changes in microstructure in tempered martensite. In this study, multi-aspect characterization using various advanced characterization techniques were performed, with an aim to clarify the low-temperature tempering behaviors of high-carbon martensitic steels. An Fe-0.8 mass% binary alloy was mainly used in this study, and 4 ternary alloys with further 2 at% addition of Mn, Si, Cr or Al, were also investigated for comparison. All the alloys were water quenched after austenitization to obtain the as-quenched martensite as the starting microstructure. Tempering processes were performed either by continuous heating or isothermal holding under various conditions. Afterwards, the changes in physical properties of tempered martensite were analyzed via calorimetry, dilatometry, and resistometry, whereas the microstructural evolutions were characterized via transmission electron microscopy, in-situ neutron diffraction, and three-dimensional atom probe tomography. The experimental results revealed the continuous occurrence of different tempering stages, including carbon clustering, precipitation of metastable iron carbide, decomposition of retained austenite, and precipitation of cementite. In addition, the tetragonality of martensite became continuously lowered due to the reduction in solute carbon content by tempering. Among all the investigated elements, the addition of Al was found to have the largest retardation effects on the tempering kinetics, which was caused by its suppression effect on carbon diffusivity.
Zhang, Y.*; 宮本 吾郎*; 古原 忠*; 丸澤 賢人*; 工藤 航平*; 諸岡 聡
no journal, ,
In this study, following our previous work on low-temperature tempering kinetics, multi-aspect characterization (in-situ neutron diffraction, TEM and 3DAP) via combining various traditional and advanced experimental approaches was performed, with an aim to thoroughly elucidate the low-temperature tempering behaviors and microstructural evolutions in martensite. As the result, the lattice parameters of a- and c-axes of martensite became increased and decreased, respectively, during continuous heating, resulting in continuous weakening of its tetragonality especially in the temperature range of the 1st stage of 
/-carbide precipitation (340 K 
500 K). On the other hand, the lattice parameter of austenite stopped increasing at 450 K much earlier before the onset of the 2nd stage, indicated the occurrence of carbon depletion.
