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論文

回折法を利用したLPSO型マグネシウム合金における階層的変形機構に関する研究

城鮎美*; 菖蒲敬久; 萩原幸司*; 渡邉真史*

SPring-8/SACLA利用研究成果集(インターネット), 10(5), p.438 - 446, 2022/10

https://doi.org/10.18957/rr.10.5.438

長周期積層型(LPSO)マグネシウム合金は、濃度と構造の変調が同期しており、軽量かつ高強度・高耐熱性という性質を併せ持った新規材料である。LPSO相の局所的な格子ひずみと構造変調の関係を調べるために、単相18R LPSO Mg-Zn-Y合金の圧縮下での放射光X線回折測定を実施した。圧縮応力の増加に伴い、格子ひずみの増加が確認されるとともに、0 0 L回折面からの回折強度の大小が入れ替わる現象が発生した。解析の結果、回折強度の変化はイットリウム原子の特徴的な変位によるものであり、弾性変形から塑性変形への移行に大きな影響を与える可能性を明らかにした。

論文

In situ X-ray diffraction study of the oxide formed on alloy 600 in borated and lithiated high-temperature water

渡邉真史*; 米澤利夫*; 菖蒲敬久; 城鮎美; 庄子哲雄*

Corrosion, 72(9), p.1155 - 1169, 2016/09

https://doi.org/10.5006/1994

被引用回数：1 パーセンタイル：6.28(Materials Science, Multidisciplinary)

In situ X-ray diffraction (XRD) measurements of the oxide film formed on Alloy 600 in borated and lithiated high-temperature water were conducted to demonstrate a capability to investigate rapid changes in oxide films during transient water chemistry conditions. In the presence of dissolved hydrogen (DH) = 30 cm $^{3}$ /kg [H $_{2}$ O] and dissolved oxygen (DO) 0.06 ppm, only spinel oxides were detected and no significant NiO peak was found even after 1,220 h exposure. By contrast, once the DO was increased to 8 ppm, a NiO peak grew rapidly. Within 7 h, the amount of NiO became comparable to that of spinel oxide. However, when DO was decreased again below 0.3 ppm and DH was increased up to 30 cm $^{3}$ /kg [H $_{2}$ O], the ratio of NiO to spinel did not change during 10 h. Thus, the rate of dissolution of NiO in DH = 30 cm $^{3}$ /kg water seemed to be lower than the growth rate of NiO in high DO conditions.

論文

In situ X-ray diffraction measurement method for investigating the oxides films on austenitic stainless steel in simulated pressurized water reactor primary water

渡邉真史*; 米澤利夫*; 菖蒲敬久; 庄子哲雄*

Corrosion, 71(10), p.1224 - 1236, 2015/10

https://doi.org/10.5006/1690

被引用回数：3 パーセンタイル：17.9(Materials Science, Multidisciplinary)

Synchrotron X-ray diffraction analytical techniques have been used to investigate the structure of oxide films formed on Type 316L (UNS S31603) austenitic stainless steel in simulated pressurized water reactor primary water. The observed layer structures of the oxide films changed depending on the dissolved hydrogen concentration (DH) in PWR primary water. In two cases, where DH = 5 cm $^{3}$ /kg (H $_{2}$ O) or 30 cm $^{3}$ /kg (H $_{2}$ O), a (Ni $_{x}$ Fe( $_{1-x}$ ))Fe $_{2}$ O $_{4}$ -type spinel oxide was observed as the outer oxide, and a FeCr $_{2}$ O $_{4}$ -type spinel oxide was detected as the thin inner oxide. When DH = 30 cm $^{3}$ /kg (H $_{2}$ O), the Fe:Ni ratio in the (Ni $_{x}$ Fe( $_{1-x}$ ))Fe $_{2}$ O $_{4}$ outer spinel oxide was much larger than when DH = 5 cm $^{3}$ /kg (H $_{2}$ O). In addition, sequential in situ measurements when the hydrogen concentration varied from 5 cm $^{3}$ /kg (H $_{2}$ O) to 30 cm $^{3}$ /kg (H $_{2}$ O) also demonstrated that the oxide layer structure seemed to adjust its characteristic composition as a function of the DH.