Elucidation of the formation process and shape determining factors of GP zones and nanoclusters in Al-Cu and Al-Mg-Si alloys

Shoji, Mizuki*; Kurihara, Kensuke*; Lobzenko, I.; Tsuru, Tomohito; Serizawa, Ai*

Keikinzoku, 74(12), p.535 - 545, 2024/12

https://doi.org/10.2464/jilm.74.535

While Plate-like Guinier-Preston (GP) zones are formed during aging process in Al-Cu alloys, spherical nanocluster formation occurs in the early stage of aging in Al-Mg-Si alloys. Unlike well-known GP (I) zone in Al-Cu, there is no specific configurations within the nanocluster. However, the solute concentration and local configuration should play decisive role in subsequent formation of precipitations. In the present study, the first-principles calculations were performed to investigate the factors determining the stable shape during the formation process of GP zones and clusters in Al-Cu and Al-Mg-Si alloys. As a result of formation energy of three-body bonds, the Cu-Cu-Cu triplet with the bond angle of 90deg was the most stable. Monte Carlo simulations with newly developed machine-learning potential were then performed, and consequently the segregation of Cu atom formed with bond angle of 90deg are observed more frequently. In contrast, three-body triplet in Al-Mg-Si alloy was most stable without any specific directional anisotropy, when the bond angle was 60deg, resulting in the formation of spherical nanoclusters. These results suggest that the intrinsic feature of the stability of local bonding dominates the shape of GP zones and nanoclusters, in which planar- or spherical-like cluster is formed.

Progress of divertor simulation research toward the realization of detached plasma using a large tandem mirror device

Nakashima, Yosuke*; Takeda, Hisahito*; Ichimura, Kazuya*; Hosoi, Katsuhiro*; Oki, Kensuke*; Sakamoto, Mizuki*; Hirata, Mafumi*; Ichimura, Makoto*; Ikezoe, Ryuya*; Imai, Tsuyoshi*; et al.

Journal of Nuclear Materials, 463, p.537 - 540, 2015/08

https://doi.org/10.1016/j.jnucmat.2014.12.063

CeBr gamma-ray spectrometer toward the decommissioning of the Fukushima Daiichi Nuclear Power Station

Kaburagi, Masaaki; Shimazoe, Kenji*; Otaka, Yutaka*; Foong, W. S.*; Uenomachi, Mizuki*; Kamada, Kei*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.

no journal, , 

no abstracts in English

Measurements of absolute hydrogen gas pressure in the divertor module in GAMMA 10 and effects on reduction of thermal and particle loads onto the V-shaped target

Fukumoto, Masakatsu; Ichimura, Kazuya*; Nakashima, Yosuke*; Takeda, Hisahito*; Iwamoto, Miki*; Hosoda, Yasunari*; Sakamoto, Mizuki*; Kubo, Hirotaka; Shoji, Mamoru*

no journal, , 

no abstracts in English

Performance study of multi cubic high energy -ray spectrometric system for the decommissioning of the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station

Kaburagi, Masaaki; Shimazoe, Kenji*; Otaka, Yutaka*; Uenomachi, Mizuki*; Kamada, Kei*; Kim, K. J.*; Yoshino, Masao*; Shoji, Yasuhiro*; Yoshikawa, Akira*; Takahashi, Hiroyuki*; et al.

no journal, , 

The retrieval of the nuclear fuel debris, which is the substance including melted nuclear fuel and structural materials, will be started from fiscal 2021. Then, as a non-destructive analysis technology of the nuclear fuel debris, a -ray spectroscopy system is being developed to measure high energy rays due to Eu and nuclear reactions under high dose rate, which was composed of a CeBr cubic, photomultiplier tube, and fast signal processing unit. This presentation reports that the exposure study of the detector system was performed for a Co field at the dose rates of up to 750 mSv/h, and the detector response was investigated at each dose rate.