The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform

Wanqi Jie - One of the best experts on this subject based on the ideXlab platform.

  • Neutron Irradiation-induced defects in Cd0.9Zn0.1Te:In crystals
    Materials Science in Semiconductor Processing, 2019
    Co-Authors: Lei Bao, Gangqiang Zha, Binbin Zhang, Jiangpeng Dong, Wanqi Jie
    Abstract:

    Abstract The survivability of γ-ray detector in radiation environment of energetic Neutrons is a key issue for its application in spacecraft, accelerator, nuclear reactor, etc., especially for the case of CdZnTe detectors. Nevertheless, very little attention has been paid to the radiation damage mechanism of detectors and the evolution of radiation-induced defects in the detector medium, i.e. Cd0.9Zn0.1Te:In crystals. We proposed and simulated the radiation defects type and amount of Cd0.9Zn0.1Te:In crystals after Neutron Irradiation with the Monte-Carlo software SRIM. The calculated data are also compared with experimental results of detector performance and the crystal defects obtained using thermally stimulated current (TSC) measurement. We also discuss the influence of defect concentrations on crystal resistivity and detector energy resolution. It was shown that the concentration of vacancies, interstitials, and their related defects increased after Neutron Irradiation, which could be the reason for the worsening of Cd0.9Zn0.1Te:In γ-ray detector performance after the Neutron Irradiation.

Akira Hasegawa - One of the best experts on this subject based on the ideXlab platform.

  • Neutron Irradiation effects on the mechanical properties of powder metallurgical processed tungsten alloys
    Journal of Nuclear Materials, 2020
    Co-Authors: Takeshi Miyazawa, Makoto Fukuda, Yutai Katoh, L M Garrison, Josina W Geringer, Tatsuya Hinoki, Akira Hasegawa
    Abstract:

    Abstract Neutron Irradiation effects on the tensile properties of Pure W, K-doped W, W–3%Re, and K-doped W–3%Re were examined under the US-Japan collaboration project PHENIX. The fission Neutron Irradiation experiments were carried out up to 0.74 dpa at 600 °C and 800 °C. Pure W (SR) showed Irradiation hardening and loss of ductility after Irradiation at 600 °C and 800 °C. K-doped W–3%Re (SR) also exhibited Irradiation hardening but was ductile after Irradiation. Characteristic points of the K-doped W–3%Re (SR) are small grain size and layered structure. The stress-relief treatment and the layered structure may improve the ductility of powder-metallurgy W alloys after Neutron Irradiation, so a combination of K-doping and Re addition would be beneficial to improve Irradiation resistance.

  • microstructural development of tungsten and tungsten rhenium alloys due to Neutron Irradiation in hfir
    Journal of Nuclear Materials, 2014
    Co-Authors: Makoto Fukuda, Shuhei Nogami, Akira Hasegawa, Kiyohiro Yabuuchi, Teruya Tanaka
    Abstract:

    Abstract The microstructural development of pure tungsten (W) and tungsten–rhenium (Re) alloys due to Neutron Irradiation in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, TN, USA, was investigated in this work. The Irradiation conditions were ∼1 displacements per atom (dpa) at 500 and 800 °C. After the Neutron Irradiation, microstructural observations were performed using a transmission electron microscope (TEM). Large amounts of precipitates identified as sigma- and chi-phases were observed in not only the W–Re alloys but also in the pure W after the Neutron Irradiation. The precipitates observed in the pure W were coarse and larger than those in the W–Re alloys. This was considered to be caused by the transmutation products of W and Re, namely, Re and osmium (Os), respectively, under Irradiation in the HFIR with a higher contents of thermal Neutron flux.

  • Microstructure development of dispersion-strengthened tungsten due to Neutron Irradiation
    Journal of Nuclear Materials, 2014
    Co-Authors: Makoto Fukuda, Shuhei Nogami, Akira Hasegawa, Kiyohiro Yabuuchi
    Abstract:

    Abstract This work investigated the effects of Neutron Irradiation on microstructure development in pure and dispersion-strengthened W (i.e., lanthanum (La)-doped W and potassium (K)-doped W). The Irradiation experiments were performed in the experimental fast reactor Joyo. The Irradiation temperature and damage were in the range 531–756 °C and 0.42–0.47 dpa, respectively. Voids, dislocation loops, and black dots were observed in pure, La-doped, and K-doped W after Neutron Irradiation with almost identical size and number density of the defect clusters. Likewise, the hardening of pure, La-doped, and K-doped W because of Neutron Irradiation was nearly identical. Thus, the dispersion of the second phase in La-doped and K-doped W did not affect the microstructure development and Irradiation hardening in tungsten under Neutron-Irradiation conditions in this work.

  • property change of advanced tungsten alloys due to Neutron Irradiation
    Journal of Nuclear Materials, 2013
    Co-Authors: Makoto Fukuda, Takashi Tanno, Shuhei Nogami, Akira Hasegawa, Hiroaki Kurishita
    Abstract:

    Abstract This study investigates the effect of Neutron Irradiation on the functional properties of pure tungsten (W) and advanced tungsten alloys (e.g., lanthanum (La)-doped W, potassium (K)-doped W, and ultra-fine-grained (UFG) W–TiC alloys) tested in the Japan Materials Testing Reactor (JMTR) or experimental fast reactor Joyo. The Irradiation temperature and damage were in the range 804–1073 K and 0.15–0.47 dpa, respectively. TEM images of all samples after 0.42 dpa Irradiation at 1023 K showed voids, black dots, and dislocation loops, indicating that similar damage structures were formed in pure W, La-doped W, K-doped W, and UFG W–0.5 wt% TiC. The electrical resistivity of all specimens increased following Neutron Irradiation. Nearly identical electrical resistivity and Irradiation hardening were observed in pure W, La-doped W, and K-doped W. The electrical resistivity of UFG W–TiC was higher than that of other specimens before and after Irradiation, which may be attributed to its ultra-fine-grain structure, as well as the presence of impurities introduced during the alloying process. Compared to the other specimens, the UFG W–TiC was more resistant to Irradiation hardening.

  • Neutron Irradiation behavior of tungsten
    Materials Transactions, 2013
    Co-Authors: Akira Hasegawa, Takashi Tanno, Makoto Fukuda, Shuhei Nogami
    Abstract:

    Tungsten (W) is a candidate for the plasma facing component material of fusion reactors. During fusion reactor operation, not only displacement damage but also transmutation elements such as rhenium (Re) and osmium (Os) are produced in W by Neutron Irradiation. To understand the Irradiation response of W in a fusion reactor, Irradiation effects on hardening, microstructure development and electric resistivity of pure W and W­Re­Os alloys are studied using fission reactor Irradiation. In the low-dpa region ( 1 dpa) Irradiation. The hardening was caused by the Irradiation-induced precipitation of WRe (·­phase) and WRe3 (»­phase). Os was more effective in the Irradiation hardening than Re owing to the similar Irradiation-induced precipitate formation even in low-dpa region. On the bases of these results, the alloy design of W for fusion reactor applications is suggested. [doi:10.2320/matertrans.MG201208]

Lei Bao - One of the best experts on this subject based on the ideXlab platform.

  • Neutron Irradiation-induced defects in Cd0.9Zn0.1Te:In crystals
    Materials Science in Semiconductor Processing, 2019
    Co-Authors: Lei Bao, Gangqiang Zha, Binbin Zhang, Jiangpeng Dong, Wanqi Jie
    Abstract:

    Abstract The survivability of γ-ray detector in radiation environment of energetic Neutrons is a key issue for its application in spacecraft, accelerator, nuclear reactor, etc., especially for the case of CdZnTe detectors. Nevertheless, very little attention has been paid to the radiation damage mechanism of detectors and the evolution of radiation-induced defects in the detector medium, i.e. Cd0.9Zn0.1Te:In crystals. We proposed and simulated the radiation defects type and amount of Cd0.9Zn0.1Te:In crystals after Neutron Irradiation with the Monte-Carlo software SRIM. The calculated data are also compared with experimental results of detector performance and the crystal defects obtained using thermally stimulated current (TSC) measurement. We also discuss the influence of defect concentrations on crystal resistivity and detector energy resolution. It was shown that the concentration of vacancies, interstitials, and their related defects increased after Neutron Irradiation, which could be the reason for the worsening of Cd0.9Zn0.1Te:In γ-ray detector performance after the Neutron Irradiation.

Shuhei Nogami - One of the best experts on this subject based on the ideXlab platform.

  • microstructural development of tungsten and tungsten rhenium alloys due to Neutron Irradiation in hfir
    Journal of Nuclear Materials, 2014
    Co-Authors: Makoto Fukuda, Shuhei Nogami, Akira Hasegawa, Kiyohiro Yabuuchi, Teruya Tanaka
    Abstract:

    Abstract The microstructural development of pure tungsten (W) and tungsten–rhenium (Re) alloys due to Neutron Irradiation in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, TN, USA, was investigated in this work. The Irradiation conditions were ∼1 displacements per atom (dpa) at 500 and 800 °C. After the Neutron Irradiation, microstructural observations were performed using a transmission electron microscope (TEM). Large amounts of precipitates identified as sigma- and chi-phases were observed in not only the W–Re alloys but also in the pure W after the Neutron Irradiation. The precipitates observed in the pure W were coarse and larger than those in the W–Re alloys. This was considered to be caused by the transmutation products of W and Re, namely, Re and osmium (Os), respectively, under Irradiation in the HFIR with a higher contents of thermal Neutron flux.

  • Microstructure development of dispersion-strengthened tungsten due to Neutron Irradiation
    Journal of Nuclear Materials, 2014
    Co-Authors: Makoto Fukuda, Shuhei Nogami, Akira Hasegawa, Kiyohiro Yabuuchi
    Abstract:

    Abstract This work investigated the effects of Neutron Irradiation on microstructure development in pure and dispersion-strengthened W (i.e., lanthanum (La)-doped W and potassium (K)-doped W). The Irradiation experiments were performed in the experimental fast reactor Joyo. The Irradiation temperature and damage were in the range 531–756 °C and 0.42–0.47 dpa, respectively. Voids, dislocation loops, and black dots were observed in pure, La-doped, and K-doped W after Neutron Irradiation with almost identical size and number density of the defect clusters. Likewise, the hardening of pure, La-doped, and K-doped W because of Neutron Irradiation was nearly identical. Thus, the dispersion of the second phase in La-doped and K-doped W did not affect the microstructure development and Irradiation hardening in tungsten under Neutron-Irradiation conditions in this work.

  • property change of advanced tungsten alloys due to Neutron Irradiation
    Journal of Nuclear Materials, 2013
    Co-Authors: Makoto Fukuda, Takashi Tanno, Shuhei Nogami, Akira Hasegawa, Hiroaki Kurishita
    Abstract:

    Abstract This study investigates the effect of Neutron Irradiation on the functional properties of pure tungsten (W) and advanced tungsten alloys (e.g., lanthanum (La)-doped W, potassium (K)-doped W, and ultra-fine-grained (UFG) W–TiC alloys) tested in the Japan Materials Testing Reactor (JMTR) or experimental fast reactor Joyo. The Irradiation temperature and damage were in the range 804–1073 K and 0.15–0.47 dpa, respectively. TEM images of all samples after 0.42 dpa Irradiation at 1023 K showed voids, black dots, and dislocation loops, indicating that similar damage structures were formed in pure W, La-doped W, K-doped W, and UFG W–0.5 wt% TiC. The electrical resistivity of all specimens increased following Neutron Irradiation. Nearly identical electrical resistivity and Irradiation hardening were observed in pure W, La-doped W, and K-doped W. The electrical resistivity of UFG W–TiC was higher than that of other specimens before and after Irradiation, which may be attributed to its ultra-fine-grain structure, as well as the presence of impurities introduced during the alloying process. Compared to the other specimens, the UFG W–TiC was more resistant to Irradiation hardening.

  • Neutron Irradiation behavior of tungsten
    Materials Transactions, 2013
    Co-Authors: Akira Hasegawa, Takashi Tanno, Makoto Fukuda, Shuhei Nogami
    Abstract:

    Tungsten (W) is a candidate for the plasma facing component material of fusion reactors. During fusion reactor operation, not only displacement damage but also transmutation elements such as rhenium (Re) and osmium (Os) are produced in W by Neutron Irradiation. To understand the Irradiation response of W in a fusion reactor, Irradiation effects on hardening, microstructure development and electric resistivity of pure W and W­Re­Os alloys are studied using fission reactor Irradiation. In the low-dpa region ( 1 dpa) Irradiation. The hardening was caused by the Irradiation-induced precipitation of WRe (·­phase) and WRe3 (»­phase). Os was more effective in the Irradiation hardening than Re owing to the similar Irradiation-induced precipitate formation even in low-dpa region. On the bases of these results, the alloy design of W for fusion reactor applications is suggested. [doi:10.2320/matertrans.MG201208]

  • Indentation Properties of Silicon Carbide after Neutron Irradiation and Helium Implantation
    IOP Conference Series: Materials Science and Engineering, 2011
    Co-Authors: Shuhei Nogami, Akira Hasegawa
    Abstract:

    The hardness, elastic modulus and fracture toughness of the CVD-SiC after Neutron Irradiation up to 0.4 dpa at 600°C and up to 0.6 dpa at 800°C and after He implantation up to 800 appm at 750°C were evaluated using the indentation technique. The effect of Neutron Irradiation was discussed with the previous data (0.2–7.7 dpa, 80–1050°C). The hardness slightly increased at all Neutron Irradiation doses and temperatures. It was independent on the Neutron Irradiation dose above a saturation value. Almost no influence of the He implantation on the hardness was observed. The rapid reduction of elastic modulus with the Neutron Irradiation temperature below 100°C was observed. However, it gradually recovered and showed almost the same value as the unirradiated one when irradiated above 800°C. About 35% reduction of the elastic modulus due to He implantation was observed. Small reduction of fracture toughness below 400°C, and increase with increased Neutron Irradiation temperature to 1000°C was observed. About 30% reduction of the fracture toughness due to He implantation was observed, which was mainly attributed to the reduction of elastic modulus and the increment of crack length under indentation.

Y. Chen - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Neutron Irradiation on hardening in MgO crystals
    Physical Review B, 2002
    Co-Authors: D. Cáceres, I. Vergara, R. González, Y. Chen
    Abstract:

    Using a nanoindentation technique, hardness and Young's modulus were determined in both nominally pure MgO and lithium-doped MgO crystals, before and after Neutron Irradiation in the dose range ${10}^{15}\char21{}{10}^{19} {\mathrm{n}/\mathrm{c}\mathrm{m}}^{2}.$ The resulting defects were monitored by optical-absorption spectroscopy. The concentrations of single oxygen vacancies and higher-order point defects involving oxygen vacancies increase with Neutron dose. A constant value of $(290\ifmmode\pm\else\textpm\fi{}15)$ GPa for the Young's modulus was measured in all the crystals, indicating that the elastic properties are not influenced by either impurities or defects produced by Irradiation. Hardness increases with Neutron dose and is independent of the presence of lithium in the crystal. Neutron-irradiated crystals contain oxygen vacancies, higher-order point defects, and interstitials, whereas thermochemically reduced (TCR) crystals contain oxygen vacancies. Comparison between a Neutron irradiated and a TCR MgO crystal containing similar concentrations of oxygen vacancies, shows that 70% of the hardening by Neutron Irradiation is produced by interstitials, 30% by oxygen vacancies, and a negligible amount by higher-order point defects.