Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloy through multi-modal 3D image-based simulation

Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*

International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03

https://doi.org/10.1016/j.ijplas.2024.103897

Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.

High proton radiation tolerance of InAsSb quantum-well-based micro-Hall sensors

Abderrahmane, A.*; Ko, P. J.*; Okada, Hiroshi*; Sato, Shinichiro; Oshima, Takeshi; Shibasaki, Ichiro*; Sandhu, A.*

IEEE Electron Device Letters, 35(12), p.1305 - 1307, 2014/12

https://doi.org/10.1109/LED.2014.2359879

Tolerance of AlInSb/InAsSb/AlInSb heterostructures quantum-well-based micro-Hall sensors against proton irradiation of 380 keV and proton fluence in the range 10 and 10 (proton/cm) is reported. Defects and deep levels induced by proton irradiation into the heterostructures caused decreases in the mobility of the micro-Hall sensors. Degradation of the magnetic sensitivity started at a proton fluence of 10 (proton/cm) and continued with increasing proton fluence. The variation of the micro-Hall sensors sensitivity was minimal in low doped AlInSb/InAsSb/AlInSb heterostructure quantum wells. These micro-Hall sensors were operable even at proton fluence of 10 (proton/cm), which makes these devices suitable for space applications with lifetime of thousands of years in the outer space.

Effect of annealing on proton irradiated AlGaN/GaN based micro-Hall sensors

Abderrahmane, A.*; Takahashi, Hiroki*; Tashiro, Tatsuya*; Ko, P. J.*; Okada, Hiroshi*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*

AIP Conference Proceedings 1585, p.123 - 127, 2014/02

https://doi.org/10.1063/1.4866629

The effect of annealing at 673 K on irradiated micro-Hall sensors irradiated with protons at 380 keV and fluences of 1 cm, 1 cm, 1 cm is reported. Cathodoluminescence measurements were carried out at room temperature before and after annealing and showed improvement in the band edge band emission of the GaN layer. After annealing a sensor irradiated by 1 cm the device became operational with improvements in its magnetic sensitivity. All irradiated sensors showed improvement in their electrical characteristics after annealing.

Effect of proton irradiation on AlGaN/GaN micro-Hall sensors

Abderrahmane, A.*; Koide, Shota*; Okada, Hiroshi*; Takahashi, Hiroki*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*

Applied Physics Letters, 102(19), p.193510_1 - 193510_4, 2013/05

https://doi.org/10.1063/1.4805357

The magnetoelectric properties of AlGaN/GaN micro-Hall effect sensors were studied after 380 keV proton irradiation. After irradiation the current-voltage measurements, stability of the magnetic sensitivity of the sensors, and the sheet electron density were degraded with a dramatic decrease of the electron mobility at high temperatures. Raman spectroscopy showed a degradation in the crystalline quality of GaN crystal, but there was no change in the strain.

Robust Hall effect magnetic field sensors for operation at high temperatures and in harsh radiation environments

Abderrahmane, A.*; Koide, Shota*; Sato, Shinichiro; Oshima, Takeshi; Sandhu, A.*; Okada, Hiroshi*

IEEE Transactions on Magnetics, 48(11), p.4421 - 4423, 2012/11

https://doi.org/10.1109/TMAG.2012.2196986

Recent industrial trends indicate increasing demand for Hall effect sensors for monitoring magnetic fields under extreme conditions such as high temperatures and under harmful radiation conditions. In this study, robust and high sensitivity Hall effect sensors using AlGaN/GaN heterostructures with a two-dimensional electron gas at the heterointerface were fabricated, and their magnetic properties were investigated. The AlGaN/GaN 2DEG Hall sensors were stable to at least 400 C and even after irradiation of 380 keV protons at the fluence of 1 10 /cm. The results showed that the AlGaN/GaN 2DEG Hall sensors had superior radiation tolerance to AlGaAs/GaAs and AlInSb/InAsSb/AlInSb magnetic sensors.

Study of ion-beam-induced damage and luminescence properties in terbium-implanted AlGaN

Park, J.-H.*; Wakahara, Akihiro*; Okada, Hiroshi*; Furukawa, Yuzo*; Kim, Y.-T.*; Chang, H.-J.*; Song, J.*; Shin, S.*; Lee, J.-H.*; Sato, Shinichiro; et al.

Japanese Journal of Applied Physics, 49(3), p.032401_1 - 032401_5, 2010/03

https://doi.org/10.1143/JJAP.49.032401

The Change of water quality during rain event at Ijira river

Takahashi, Shinya*; Inoue, Takanobu*; Tsushima, Koji*; Sakioka, Masamichi*; Matsunaga, Takeshi

Kankyo Kogaku Kenkyu Rombunshu, 46, p.565 - 572, 2009/00

This study analyzed the changes of water quality during rain events at Ijira river, a mountain stream in Gifu Prefecture, by measured the major ion concentration, pH, electric conductivity, discharge, and hydrograph separation using deuterium isotope ratio of the water. During rain events, where the discharge is increase, almost all of the major ion concentration, pH and electric conductivity were decreased. We also found that the correlation of the changes of pH and the changes of electric conductivity with precipitation were negative. The result of hydrograph separation shows that the ratio of surface runoff for discharge is increased with an increased of the precipitation, and also increased in the high precipitation. It was shown that the major factor of the changes of water quality in this study site is the contribution of surface runoff.

Stream discharge of metals and rare earth elements in rainfall events in a forested catchment

Matsunaga, Takeshi; Tsuzuki, Katsunori; Yanase, Nobuyuki; Hanzawa, Yukiko; Naganawa, Hirochika; Inoue, Takanobu*; Yamada, Toshiro*; Miyata, Akifumi*

Proceedings of International Symposium on Environmental Modeling and Radioecology, p.243 - 246, 2007/03

The aim of this work is to obtain a fundamental scheme of stream discharge of inorganic toxic materials derived from Characteristics of the stream discharge of metallic elements were investigated in two forested catchments in the Oda River and the Ijira River watersheds. Precipitations, stream water and soil water samples were collected in raining events and were analyzed for inorganic elements, dissolved organic carbon and isotopic abundance of deuterium. Results revealed an accelerated discharge of specific metals of Cu, Sb and Cr and all the studied REE in dissolved form. This feature was commonly found in the two catchments. The specific metals are strongly suspected to be of anthropogenic origin. An analysis of hydrological discharge, using chemical and isotopic tracers, suggested that the increased discharge of the metals originate from their deposits on the ground surface and/or instantaneous resuspension of stream sediment. Contrary, REE discharge was tightly coupled with that of dissolved humic substances.

Study of electron irradiation-induced defects in CuInSe and CuInGaSe by electron spin resonance

Okada, Hiroshi*; Lee, H.-S.*; Wakahara, Akihiro*; Yoshida, Akira*; Oshima, Takeshi; Kamiya, Tomihiro

Solar Energy Materials and Solar Cells, 90(1), p.93 - 99, 2006/01

https://doi.org/10.1016/j.solmat.2005.03.005

no abstracts in English

Improvement of luminescence capability of Tb-related emission by AlGaN

Nakanishi, Yasuo*; Wakahara, Akihiro*; Okada, Hiroshi*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi

Physica Status Solidi (B), 240(2), p.372 - 375, 2003/11

https://doi.org/10.1002/pssb.200303479

Luminescence propeties of Tb-doped AlGaN were studied. The samples were grown on sapphire substrates using OMVPE. Tb implantation was cariied out to introduce Tb into samples. After implantation, samples were annealed at 1000 to 1150 C in 10% NH diluted with N. The luminescence intensity for AlGaN x=0.1 is 5 times stronger than that for x=0 at 14 K. The luminesecence intensity for GaN rapidly decreases with temperature and its activation enegy is 7.8 meV. With increasing Al content, the activation enegy increases, and the activation energy for AlGaN is 70 meV.