Microstructures and hardness of BCC phase iron-based high entropy alloy Fe-Mn-Cr-V-Al-C

Wakai, Eiichi; Noto, Hiroyuki*; Shibayama, Tamaki*; Furuya, Kazuyuki*; Ando, Masami*; Kamada, Takaharu*; Ishida, Taku*; Makimura, Shunsuke*

Materials Characterization, 211, p.113881_1 - 113881_10, 2024/05

https://doi.org/10.1016/j.matchar.2024.113881

The microstructures and mechanical properties of bcc iron-based high entropy alloy (HEA) Fe-20Mn-15Cr-10V-10Al-2.5C (in at%) without Co and Ni elements have been investigated for applications in fields such as accelerator-target system, nuclear reactors and magnetic motors in aircraft and automobiles. This alloy was normalized at 1150C for 2 hr and then water quenched, and it was heated at 800C for 10 min and then water quenched. The alloy had a bcc-phase and vanadium carbides with 2-3 m arranging along grain boundaries, and the Vickers hardness was 520 Hv, harder than pure tungsten. Magnetic domain structure was observed in phase differential contrast method in scanning transmission electron microscope, and the micro-size magnetic domains in grain and sub micro size ones were formed near surface, and it is attractive to the magnetic motor field application. Element distribution in nano scale (20 nm) was observed in matrix, and the presence of crystal lattice disorder in the atomic level region was seen. Very high performance for radiation resistance was confirmed with no irradiation hardening at 300 and 500 C to 1 dpa. It can be speculated that this is due to irradiation-induced nanoscale concentration changes and strain relaxation in the HEA. These properties are very attractive in application of several fields.

Recent improvement and evaluation of radiation resistance and magnetic properties of high entropy alloys and their applications

Wakai, Eiichi; Noto, Hiroyuki*; Shibayama, Tamaki*; Furuya, Kazuyuki*; Wakui, Takashi; Ando, Masami*; Makimura, Shunsuke*; Ishida, Taku*

Science Talks (Internet), 8, p.100278_1 - 100278_4, 2023/12

https://doi.org/10.1016/j.sctalk.2023.100278

High entropy alloys tend to combine high strength with good ductility due to their inherent properties. This material is considered as a promising new material not only for higher-performance future general industrial applications, but also for increasing the durability and range of application of radiation-affected equipment in nuclear and radiation environments, and has been rapidly gaining attention in recent years. In this study, two types of high-entropy alloys (Fe-Mn-V-Cr-Al-C and Fe-Si-W-Cr-V) composed of low-radioactive elements (without Ni and Co) were prepared and their basic properties were evaluated for application as new functional materials to be used under radiation in high-energy accelerator target system components, nuclear reactors, fusion reactors, etc. and their basic properties were evaluated. The two materials under development in this study have unique properties in the following respects. The former is expected to be developed as a basic research for high-power motor materials as a new structural material and magnetic properties sharing the features of high strength and low radiation. On the other hand, the latter is expected to be applied as a new functional material in new engineering fields by mixing tungsten, which has the highest melting point among metallic elements, with vanadium, which has a considerably higher melting point, to raise the melting point of the alloy and to design an alloy with high strength.

Measurement of displacement cross-sections of copper and iron for proton with kinetic energies in the range 0.4 - 3 GeV

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*

Journal of Nuclear Science and Technology, 57(10), p.1141 - 1151, 2020/10

https://doi.org/10.1080/00223131.2020.1771453

To estimate the structural damages of materials in accelerator facilities, displacement per atom (dpa) is widely employed as a damage index, calculated based on the displacement cross-section obtained using a calculation model. Although dpa is applied as standard, the experimental data of the displacement cross-section for a proton in the energy region above 20 MeV are scarce. Among the calculation models, difference of about factor 8 exist, so that the experimental data of the cross-section are crucial to validate the model. To obtain the displacement cross-section, we conducted experiments at J-PARC. The displacement cross-section of copper and iron was successfully obtained for a proton projectile with the kinetic energies, 0.4 - 3 GeV. The results were compared with those obtained using the widely utilized Norgertt-Robinson-Torrens (NRT) model and the athermal-recombination-corrected (arc) model based on molecular dynamics. It was found that the NRT model overestimates the present displacement cross-section by 3.5 times. The calculation results obtained using with the arc model based on the Nordlund parameter show remarkable agreement with the experimental data. It can be concluded that the arc model must be employed for the dpa calculation for the damage estimation of copper and iron.

Measurement of displacement cross section of structural materials utilized in the proton accelerator facilities with the kinematic energy above 400 MeV

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*

JPS Conference Proceedings (Internet), 28, p.061004_1 - 061004_6, 2020/02

https://doi.org/10.7566/JPSCP.28.061004

no abstracts in English

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 4; The Muon Facility

Higemoto, Wataru; Kadono, Ryosuke*; Kawamura, Naritoshi*; Koda, Akihiro*; Kojima, Kenji*; Makimura, Shunsuke*; Matoba, Shiro*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Strasser, P.*

Quantum Beam Science (Internet), 1(1), p.11_1 - 11_24, 2017/06

https://doi.org/10.3390/qubs1010011

A muon experimental facility, known as the Muon Science Establishment (MUSE), is one of the user facilities at the Japan Proton Accelerator Research Complex, along with those for neutrons, hadrons, and neutrinos. The MUSE facility is integrated into the Materials and Life Science Facility building in which a high-energy proton beam that is shared with a neutron experiment facility delivers a variety of muon beams for research covering diverse scientific fields. In this review, we present the current status of MUSE, which is still in the process of being developed into its fully fledged form.

J-PARC muon facility, MUSE

Miyake, Yasuhiro*; Shimomura, Koichiro*; Kawamura, Naritoshi*; Strasser, P.*; Makimura, Shunsuke*; Koda, Akihiro*; Fujimori, Hiroshi*; Nakahara, Kazutaka*; Takeshita, Soshi*; Kobayashi, Yasuo*; et al.

Journal of Physics; Conference Series, 225, p.012036_1 - 012036_7, 2010/06

https://doi.org/10.1088/1742-6596/225/1/012036

Birth of an intense pulsed muon source, J-PARC MUSE

Miyake, Yasuhiro*; Shimomura, Koichiro*; Kawamura, Naritoshi*; Strasser, P.*; Makimura, Shunsuke*; Koda, Akihiro*; Fujimori, Hiroshi*; Nakahara, Kazutaka*; Kadono, Ryosuke*; Kato, Mineo*; et al.

Physica B; Condensed Matter, 404(5-7), p.957 - 961, 2009/04

https://doi.org/10.1016/j.physb.2008.11.227

The muon science facility (MUSE) is one of the experimental areas of the J-PARC. The MUSE facility is located in the Materials and Life Science Facility (MLF), which is a building integrated to include both neutron and muon science programs. Construction of the MLF building was started at the beginning of 2004, and was recently completed at the end of the 2006 fiscal year. We have been working on the installation of the beamline components, expecting the first muon beam in the autumn of 2008.

Status of J-PARC muon science facility at the year of 2005

Miyake, Yasuhiro*; Nishiyama, Kusuo*; Kawamura, Naritoshi*; Makimura, Shunsuke*; Strasser, P.*; Shimomura, Koichiro*; Beveridge, J. L.*; Kadono, Ryosuke*; Fukuchi, Koichi*; Sato, Nobuhiko*; et al.

Physica B; Condensed Matter, 374-375, p.484 - 487, 2006/03

https://doi.org/10.1016/j.physb.2005.11.136

The construction of the Materials and Life Science building was started in the beginning of the fiscal year of 2004. After commissioning of the accelerator and beam transport sections in 2008, muon beams will be available for users in 2009. In this letter, the latest construction status of the J-PARC Muon Science Facility is reported.

Measurement of Fe displacement cross section for proton energy region between 0.4 and 3 GeV

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Iwamoto, Hiroki; Hasegawa, Shoichi; Maekawa, Fujio; Yoshida, Makoto*; Ishida, Taku*; Makimura, Shunsuke*; Nakamoto, Tatsushi*

no journal, , 

R&D of the beam window is crucial in the ADS, which serves as a partition between the accelerator and the target region. Although the displacement per atom (DPA) is used to evaluate the damage on the window, experimental data on the displacement cross section is scarce in the energy region above 20 MeV. We started to measure the displacement cross section for the protons in the energy region between 0.4 to 3 GeV. The displacement cross section can be derived by resistivity change divided by the proton flux and the resistivity change per Frankel pair on cryo-cooled sample to maintain damage. Experiments were conducted at the 3 GeV proton synchrotron at the J-PARC Center, and an iron was used as samples. As a result of comparison between the present experiment and the calculation of the NRT model, which is widely used for calculation of the displacement cross section, it was found that the calculation of the NRT model overestimates the experiment by about 3 times.

Measurement of displacement cross section for 8-GeV and 30-GeV protons

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Iwamoto, Hiroki; Hasegawa, Shoichi; Maekawa, Fujio; Yoshida, Makoto*; Ishida, Taku*; Makimura, Shunsuke*; Nakamoto, Tatsushi*

no journal, , 

In high-intensity proton accelerator facilities, the evaluation of the damage of the materials used for the beam window is essential. The damage is widely estimated by the dpa given by the displacement cross-section. Since the experimental data of the cross-section were scarce, we have started the experiment in the energy region less than 3 GeV. In order to confirm the applicability of the calculation model in the higher energy region, the cross-sections for 8 GeV and 30 GeV protons were measured at the J-PARC MR. The calculation by the NRT model showed overestimation about 2 to 4 times, as shown in the energy range below 3 GeV. It was found that the calculation with the athermal recombination correction model showed remarkably good agreement with the experiment in the energy range up to 30 GeV. It was also shown that the cross-section in the energy region above 3 GeV is proportional to the 1.2th power of the mass number of the target element.