Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
山口 正剛; 亀田 純*
no journal, ,
溶質元素の粒界偏析による粒界破壊の微視的メカニズムについて、第一原理計算と破壊靭性試験を組合せた解析を行った結果について報告する。まず、粒界の凝集エネルギーがリン,スズ,アンチモン,水素などの不純物元素の偏析によって低下し、それがき裂進展に伴う塑性仕事を減少させることが粒界破壊靱性の低下をもたらしていることを示した後、水素は破壊中も拡散可能のため、それによって粒界偏析による脆化以上の脆化効果を示すことについても報告する。
境 誠司; 松本 吉弘; 圓谷 志郎; 大伴 真名歩; Avramov, P.
no journal, ,
Elucidations of the graphene/magnetic metal interfaces are of special importance in graphene spintronics, because the spin injection from magnetic electrodes is essential for the spintronics devices. In this study, we present our results on the electronic and magnetic states of the graphene/Ni(111) interface based on the depth-resolved XMCD spectroscopy and DFT calculations. For the monolayer graphene/Ni(111) thin film, the present analysis leads to the finding that the easy magnetization direction changes from in-plane to out-of-plane in the several atomic layers of Ni on the interface. The C K-edge XMCD analysi6s clarifies that the out-of-plane spin polarization and enlargement of the spin-orbit interaction are also induced in graphene on the interface.
山下 真一郎; 関尾 佳弘; 坂口 紀史*; 柴山 環樹*; 渡辺 精一*; 粉川 博之*
no journal, ,
高密度化した対応粒界の最適分布とそれに伴うランダム粒界ネットワークの分断は、耐粒界腐食性を高める非常に有効な手法の一つであることが最近の粒界構造に関する研究で示されている。耐粒界腐食性に優れるという利点は、原子炉構造材料にとって材料選択上の重要な要素の一つであり、微量元素を含め、化学組成を一切変えることなく、単純な加工・熱処理という冶金学の基本処理のみで取得可能である点は魅力的である。本研究では、粒界工学プロセスの適用により高性能化した原子炉材料として、粒界性格分布を最適化したNi基合金(PE16)を開発し、機械的特性に及ぼす粒界工学プロセスの効果を評価するために引張強度試験を実施した。室温での引張試験の結果、粒界性格制御したPE16の引張強度は、PE16受入材のそれよりも幾分低くなったが、伸び特性においては有意な変化は認められなかった。今後は、各種試験により材料特性評価を行い、粒界性格制御による既存材料の高性能化の可能性を見極める予定である。
by the dynamic extinction of neutron radiationLiss, K. D.; Kabra, S.*; Thoennessen, L.*; Harjo, S.; Reid, M.*; Yan, K.*; Harrison, R.*; Dippenaar, R. J.*
no journal, ,
After 
+ 
Zr and Ti alloys have fully transformed into single -phase upon heating, the intensities of all -Zr Bragg reflections decrease simultaneously as a function of time. This effect represents a transition from the kinematic to the dynamic theory of diffraction due to the ever increasing crystal perfection driven by thermal recovery of the system, and has been employed to further investigate the kinetics of crystal perfection. Crystal recovery is identified as a process of dislocation annihilation, hindered by lattice friction. Furthermore, intensity increases during plastic deformation due to recreation of dislocations. Upon cooling, precipitating -phase induces strain into the perfect -crystallites, re-establishing the kinematic diffraction intensities. An Avrami analysis leads to an understanding of the nucleation and growth kinetics of the phase in its very early stages.
Al foils for methane steam reformingXu, Y.*; Ma, Y.*; 櫻井 惇也*; 出村 雅彦*; 平野 敏幸*; 寺岡 有殿; 吉越 章隆
no journal, ,
NiAl intermetallic compound is known as a promising high-temperature structural material because of its excellent high temperature strength and corrosion/oxidation resistance. The brittleness at room temperature used to be a big problem which restricted its practical application. We have overcome this problem and successfully developed thin NiAl foils using directional solidification and cold rolling. We investigated the catalytic activities of the cold-rolled NiAl foils for methane steam reforming. The effect of steam pre-treatment on the catalytic activities of the foil was also investigated. It was found that the activity of as-rolled foils increased with temperature above 873 K, while no obvious activity was detected below 873 K. The steam pre-treatment at 873 K significantly enhanced the activity in the temperature range from 873 to 1173 K. The enhanced catalytic activity was attributed to the fine pure Ni particles on the foil formed by the steam pre-treatment.