Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 179

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Effect of extrusion ratio in hot-extrusion on kink deformation during compressive deformation in an $$alpha$$Mg/LPSO dual-phase magnesium alloy monitored by ${it in situ}$ neutron diffraction

Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*

Materials Transactions, 64(4), p.766 - 773, 2023/02

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

Journal Articles

Characterization of precipitated phase in Cu-Ni-Si alloy by small-angle X-ray scattering, small angle neutron scattering and atom probe tomography

Sasaki, Hirokazu*; Akiya, Shunta*; Oba, Yojiro; Onuma, Masato*; Giddings, A. D.*; Okubo, Tadakatsu*

Materials Transactions, 63(10), p.1384 - 1389, 2022/10

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Time dependence of corrosion behavior on Ta in NaOH solutions

Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi

Materials Transactions, 63(4), p.538 - 544, 2022/04

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

The time dependence of the corrosion behavior of tantalum (Ta), which is used in nuclear fuel reprocessing equipment, in sodium hydroxide (NaOH) solutions was investigated by immersion tests, and the mechanism of the time dependence was examined via surface observations and electrochemical measurements. The immersion tests were conducted at room temperature with NaOH concentrations ranging from 1 to 7 mol/L for immersion periods of 24 to 168 h. The corrosion rate increased with the NaOH concentration but peaked with the immersion period and then decreased. The time to peak of the corrosion rate was shorter with higher NaOH concentration. The X-ray diffraction (XRD) patterns and Raman spectra of the surfaces of the specimens immersed in the 7 mol/L NaOH solution for more than 48 h showed Na$$_{8}$$Ta$$_{6}$$O$$_{19}$$ formation. The polarization resistance decreased with immersion time for all NaOH concentrations up to about 24 h after immersion. Thereafter, the polarization resistance increased with immersion time in 7 mol/L NaOH solution and remained almost constant in the other NaOH concentrations. Findings suggested that the change in the corrosion rate was affected by the film formation during immersion, since the time dependence of the polarization resistance and the sum of film resistance and charge transfer resistance had the same tendencies. The precipitation film was mainly Na$$_{8}$$Ta$$_{6}$$O$$_{19}$$ formed by the dissolution of the passivity film on Ta.

Journal Articles

${it In situ}$ TEM observation and MD simulation of frank partial dislocation climbing in Al-Cu alloy

Chen, J.*; Yoshida, Kenta*; Suzudo, Tomoaki; Shimada, Yusuke*; Inoue, Koji*; Konno, Toyohiko*; Nagai, Yasuyoshi*

Materials Transactions, 63(4), p.468 - 474, 2022/04

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

In situ electron irradiation using high-resolution transmission electron microscopy (HRTEM) was performed to visualize the Frank loop evolution in aluminium-copper (Al-Cu) alloy with an atomic-scale spatial resolution of 0.12 nm. The ${it in situ}$ HRTEM observation along the [110] direction of the FCC-Al lattice, Frank partial dislocation bounding an intrinsic stacking fault exhibited an asymmetrical climb along the $$<$$112$$>$$ direction opposed to those in the reference pure Al under an electron irradiation, with a corresponding displacement-per-atom rate of 0.055-0.120 dpa/s. The asymmetrical climb of the partial dislocation was described as pinning effects due to Cu-Cu bonding in Guinier-Preston zones by a molecular dynamics simulation.

Journal Articles

Wettability of pure metals with liquid sodium and liquid tin

Saito, Junichi; Kobayashi, Yohei*; Shibutani, Hideo*

Materials Transactions, 62(10), p.1524 - 1532, 2021/10

 Times Cited Count:2 Percentile:27.74(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Effects of thermal aging on the mechanical properties of FeCrAl-ODS alloy claddings

Yano, Yasuhide; Tanno, Takashi; Otsuka, Satoshi; Kaito, Takeji; Ukai, Shigeharu*

Materials Transactions, 62(8), p.1239 - 1246, 2021/08

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

The FeCrAl-ODS alloy claddings were manufactured and Vickers hardness, ring tensile tests and TEM observations of these claddings were performed to investigate the effects of thermal aging at 450 $$^{circ}$$C for 5,000 and 15,000 h. The age-hardening of all FeCrAl-ODS alloy cladding was found. In addition, the significant increase in tensile strength was accompanied by much larger loss of ductility. It was suggested that this age-hardening behavior was attributed to the (Ti, Al)-enriched phase ($$beta$$' phase) and the $$alpha$$' phase precipitates (content of Al is $$<$$ 7 wt%). In comparison with FeCrAl-ODS alloys with almost same chemical compositions, there was significant age-hardening in both alloys. However, the extrusion bar with no-recrystallized structures was keeping good ductility. It was suggested that this different behavior of reduction ductility was attributed to the effects of grain boundaries, dislocation densities and specimen preparation direction.

Journal Articles

Investigation of Cu diffusivity in Fe by a combination of atom probe experiments and kinetic Monte Carlo simulation

Zhao, C.*; Suzudo, Tomoaki; Toyama, Takeshi*; Nishitani, Shigeto*; Inoue, Koji*; Nagai, Yasuyoshi*

Materials Transactions, 62(7), p.929 - 934, 2021/07

 Times Cited Count:2 Percentile:27.74(Materials Science, Multidisciplinary)

We succeeded in measuring the diffusion coefficient of Cu in Fe in a low temperature range that had not been measured so far. Since the diffusion couple, which is a general method for measuring the diffusion coefficient, can be applied only at high temperature, atom probe tomography and Cu precipitation rate theory were used in this study. The estimated diffusion coefficient was found to be more reliable than that obtained in previous studies. Therefore, it is considered that the estimation by the atom probe provided higher accuracy. Furthermore, the kinetic Monte Carlo simulation revealed that the diffusion coefficient estimated by this method tends to be slightly overestimated as the temperature decreases.

Journal Articles

Analysis for the mechanism of accelerated corrosion on low alloy steel in air-solution alternating condition

Otani, Kyohei; Tsukada, Takashi; Ueno, Fumiyoshi

Materials Transactions, 62(6), p.763 - 769, 2021/06

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

In this study, the iron rust layer formed on the low alloy steel under air-solution alternating conditions was investigated by cross-sectional observation and analysis, and the mechanism of the accelerated corrosion of the steel under alternating conditions was clarified. The observations and analysis showed that the multilayered iron rust layer composed of the red rust layer (FeOOH), rust crust layer (Fe$$_{3}$$O$$_{4}$$), inner crystal (Fe$$_{3}$$O$$_{4}$$), and inner rust layer was formed on the low alloy steel. It can be considered that the multilayered iron rust layer accelerated the cathodic reaction rate of dissolved oxygen under alternating conditions. This acceleration is the reason why the corrosion rate of the low alloy steel under alternating conditions was accelerated.

Journal Articles

Synergistic effects of metal cations and sodium gluconate on the inhibition of freshwater corrosion of mild steel

Otani, Kyohei; Sakairi, Masatoshi*

Materials Transactions, 62(6), p.815 - 820, 2021/06

 Times Cited Count:1 Percentile:14.34(Materials Science, Multidisciplinary)

The synergistic effects of metal cations in a solution on the ability of sodium gluconate to inhibit the corrosion of mild steel were investigated quantitatively focus on the parameter Y, which represents the "corrosion inhibitory effect of cations" by immersion and electrochemical tests. The results of the investigations showed that the inhibition ability of gluconates improved with increasing Y value of the metal cations in model freshwater. The electrochemical and surface analyses indicated that gluconate ligands and large-Y metal cations formed a protective film with few defects on the mild steel.

Journal Articles

Hydrogen-trapping energy in screw and edge dislocations in aluminum; First-principles calculations

Yamaguchi, Masatake; Itakura, Mitsuhiro; Tsuru, Tomohito; Ebihara, Kenichi

Materials Transactions, 62(5), p.582 - 589, 2021/05

 Times Cited Count:7 Percentile:70.25(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Analysis of residual stress in steel bar processed by cold drawing and straightening

Nishida, Satoru*; Nishino, Soichiro*; Sekine, Masahiko*; Oka, Yuki*; Harjo, S.; Kawasaki, Takuro; Suzuki, Hiroshi; Morii, Yukio*; Ishii, Yoshinobu*

Materials Transactions, 62(5), p.667 - 674, 2021/05

 Times Cited Count:2 Percentile:27.74(Materials Science, Multidisciplinary)

Journal Articles

Effect of solute carbon on the characteristic hardening of steel at high temperature

Koga, Norimitsu*; Umezawa, Osamu*; Yamamoto, Masayuki*; Yamamoto, Takashi*; Yamashita, Takayuki; Morooka, Satoshi; Kawasaki, Takuro; Harjo, S.

Metallurgical and Materials Transactions A, 52(3), p.897 - 901, 2021/03

 Times Cited Count:2 Percentile:27.74(Materials Science, Multidisciplinary)

Journal Articles

Numerical interpretation of hydrogen thermal desorption spectra for iron with hydrogen-enhanced strain-induced vacancies

Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki

Metallurgical and Materials Transactions A, 52(1), p.257 - 269, 2021/01

 Times Cited Count:8 Percentile:57.56(Materials Science, Multidisciplinary)

We simulated the thermal desorption spectra of a small-size iron specimen to which was applied during charging with hydrogen atoms using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy clusters $$V_9$$, which is composed of nine vacancies and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduced the experimental spectra except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of $$V_2$$ and $$V_3$$ is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.

Journal Articles

Hydrogen trapping in Mg$$_2$$Si and Al$$_7$$FeCu$$_2$$ intermetallic compounds in aluminum alloy; First-principles calculations

Yamaguchi, Masatake; Tsuru, Tomohito; Ebihara, Kenichi; Itakura, Mitsuhiro; Matsuda, Kenji*; Shimizu, Kazuyuki*; Toda, Hiroyuki*

Materials Transactions, 61(10), p.1907 - 1911, 2020/10

 Times Cited Count:7 Percentile:52.49(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Element effects of Mn and Ge on the tuning of mechanical properties of high-entropy alloys

Lam, T.-N.*; Tsai, C.-W.*; Chen, B.-K.*; Lai, B.-H.*; Liu, H.-C*; Kawasaki, Takuro; Harjo, S.; Lin, B.-H.*; Huang, E.-W.*

Metallurgical and Materials Transactions A, 51(10), p.5023 - 5028, 2020/10

 Times Cited Count:10 Percentile:66.17(Materials Science, Multidisciplinary)

Journal Articles

Non-basal dislocation nucleation site of solid solution magnesium alloy

Somekawa, Hidetoshi*; Basha, D. A.*; Singh, A.*; Tsuru, Tomohito; Yamaguchi, Masatake

Materials Transactions, 61(6), p.1172 - 1175, 2020/06

 Times Cited Count:10 Percentile:66.17(Materials Science, Multidisciplinary)

The effect of grain boundary segregation on plastic deformation was investigated using the MgY solid solution binary alloy. Deformed microstructural observations revealed many traces of prismatic $$<a>$$ dislocations as well as basal dislocations. These dislocations were nucleated at grain boundaries with segregation of yttrium element. By comparison of material factors of binary alloy, the alloying elements having low critical resolved shear stress (CRSS) of non-basal plane and large grain boundary (twin boundary) segregation energy led to activation of non-basal dislocations in the vicinity of grain boundaries. The MgCa alloy had similar material factors and showed the same deformed microstructures as those of the alloys containing rare-earth element, which indicate that calcium element is an alternative alloying element.

Journal Articles

Neutron diffraction monitoring of as-cast Mg$$_{97}$$Zn$$_{1}$$Y$$_{2}$$ during compression and tension

Harjo, S.; Aizawa, Kazuya; Gong, W.*; Kawasaki, Takuro

Materials Transactions, 61(5), p.828 - 832, 2020/04

 Times Cited Count:4 Percentile:33.39(Materials Science, Multidisciplinary)

Journal Articles

Stability of $$gamma$$' precipitates in nickel based oxide dispersion-strengthened superalloys under high-temperature and heavy irradiation conditions

Konno, Azusa; Ono, Naoko*; Ukai, Shigeharu*; Kondo, Sosuke*; Hashitomi, Okinobu*; Kimura, Akihiko*

Materials Transactions, 60(11), p.2260 - 2266, 2019/11

 Times Cited Count:1 Percentile:7.53(Materials Science, Multidisciplinary)

A stability of cuboidal $$gamma$$' phase under heavy irradiation was studied for newly developed Ni-based Oxide Dispersion Strengthened (ODS) superalloy as a candidate for the core structural materials in VHTR or GFR. The ion irradiation was applied at 873K, 1073K, 1273K and the dose was 100 dpa. The $$gamma$$' phase remained the cuboidal shape at 873K but got out of the shape at 1073K after irradiation. Those growths can be explained by the Nelson-Hudson-Mazey (NHM) model. For the result of 1273K irradiation, however, huge $$gamma$$' phase appeared in the whole irradiated area at the post irradiation-observation. This behavior is interpreted in terms of disordering of the ordered $$gamma$$' phase due to cascade collision, and thus increasing Gibbs free energy of the disordered phase induces a change of the element distribution inside the irradiated area. The ordered $$gamma$$' phase was reproduced from the disordered state at the cooling after ion irradiation.

Journal Articles

Hydrogen desorption spectra from excess vacancy-type defects enhanced by hydrogen in tempered martensitic steel showing quasi-cleavage fracture

Saito, Kei*; Hirade, Tetsuya; Takai, Kenichi*

Metallurgical and Materials Transactions A, 50(11), p.5091 - 5102, 2019/11

 Times Cited Count:25 Percentile:85.84(Materials Science, Multidisciplinary)

An attempt was made to separate and identify hydrogen peaks desorbed from lattice defects formed by plastic-strain in the presence of hydrogen in tempered martensitic steel showing quasi-cleavage fracture using thermal desorption spectroscopy from a low temperature (L-TDS) and positron annihilation spectroscopy (PAS). The L-TDS results made it possible to separate two peaks, namely, that of the original desorption and also that of new desorption. The PAS results revealed that the new desorption obtained by L-TDS corresponded to vacancy-type defects. Hydrogen enhanced vacancy-type defect concentration, approximately 10$$^{-5}$$ order in terms of atomic ratio, formed within 1.5 mm from the fracture surface, These results indicate that the accumulation of excess vacancy-type defects enhanced by hydrogen in the local region can lead to nanovoid nucleation and coalescence in plastic deformation, resulting in quasi-cleavage fracture of tempered martensitic steel.

Journal Articles

Effect of copper addition on precipitation behavior near grain boundary in Al-Zn-Mg alloy

Matsuda, Kenji*; Yasumoto, Toru*; Bendo, A.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Marioara, C. D.*; Lervik, A.*; Holmestad, R.*; et al.

Materials Transactions, 60(8), p.1688 - 1696, 2019/08

 Times Cited Count:13 Percentile:64.7(Materials Science, Multidisciplinary)

no abstracts in English

179 (Records 1-20 displayed on this page)