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Inherited multimodal microstructure evolution of high-fracture-toughness Mg-Zn-Y-Al alloys during extrusion for the consolidation of rapidly solidified ribbons

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Journal of Magnesium and Alloys 2022年第9期10卷 2433-2445页

作者： Soya nishimoto Michiaki Yamasaki Yoshihito Kawamura Department of Materials Science Graduate School of Science and TechnologyKumamoto University2-39-1 KurokamiChuo-kuKumamoto 860-8555Japan Magnesium Research Center Kumamoto University2-39-1 KurokamiChuo-kuKumamoto 860-8555Japan

The mechanisms of multimodal microstructure evolution and the effects of microstructural factors on mechanical properties must be elucidated to design new alloys with superior *** this study,high-fracture-toughness and ductile Mg_(96.75)Zn_(0.85)Y_(2.05)Al_(0.35) alloys were developed using rapidly solidified(RS)ribbon-consolidation technique,and the inherited multimodal microstructure evolution during plastic flow consolidation of the RS ribbons was *** use of extrusion for plastic flow consolidation of the heat-treated RS ribbons produced a multimodal microstructure consisting of the worked grains with high Kernel average misorientation(KAM)angles(Group1),the ultrafine dynamically recrystallized(DRXed)grains with intermediate KAM angles(Group 2),and the fine DRXed grains with low KAM angles(Group 3).Groups 1 and 2 contribute to the alloy strengthening,while Group 3 contributes to improving ductility with strainhardening,resulting in enhancement of the fracture *** form the multimodal microstructure,it was necessary to apply plastic flow with equivalent strains of>2.3 to the heat-treated RS ribbons possessing duplex microstructures with different dispersions of the long-period stacking ordered phase.

关键词： Magnesium alloy Long-period stacking ordered phase Multimodal microstructure Rapid solidification Extrusion Dynamic recrystallization

Effects of multimodal microstructure on fracture toughness and its anisotropy of LPSO-type extruded Mg-1Zn-2Y alloys

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Journal of Magnesium and Alloys 2024年第7期12卷 2952-2966页

作者： Soya nishimoto Taiga Yasuda Koji Hagihara Michiaki Yamasaki Department of Materials Science Graduate School of Science and TechnologyKumamoto University2-39-1 KurokamiChuo-kuKumamoto 860-8555Japan Magnesium Research Center Kumamoto University2-39-1 KurokamiChuo-kuKumamoto 860-8555Japan Department of Physical Science and Engineering Nagoya Institute of technologyGokiso-choShowa-kuNagoya 466-8555Japan

The fracture toughness of extruded Mg-1Zn-2Y(at.%)alloys,featuring a multimodal microstructure containing fine dynamically recrystallized(DRXed)grains with random crystallographic orientation and coarse-worked grains with a strong fiber texture,was *** DRXed grains comprised randomly oriented equiaxedα-Mg *** contrast,the worked grains includedα-Mg and long-period stacking ordered(LPSO)phases that extended in the extrusion direction(ED).Both types displayed a strong texture,aligning the(10.10)direction parallel to the *** volume fractions of the DRXed and worked grains were controlled by adjusting the extrusion *** the longitudinal-transverse(L-T)orientation,where the loading direction was aligned parallel to the ED,there was a tendency for the conditional fracture toughness,KQ,tended to increase as the volume fraction of the worked grains ***,the KQ values in the T-L orientation,where the loading direction was perpendicular to the ED,decreased with an increase in the volume fraction of the worked *** suggests strong anisotropy in the fracture toughness of the specimen with a high volume fraction of the worked grains,relative to the test *** worked grains,which included the LPSO phase and were elongated perpendicular to the initial crack plane,suppressed the straight crack extension,causing crack deflection,and generating secondary ***,these worked grains significantly contributed to the fracture toughness of the extruded Mg-1Zn-2Y alloys in the L-T orientation.

关键词： Magnesium alloy Magnesium-zinc-yttrium Long-period stacking ordered phase Multimodal microstructure Fracture toughness

Fabrication of a model specimen for understanding micro-galvanic corrosion at the boundary ofα-Mg andβ-Mg17Al12

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Journal of Magnesium and Alloys 2023年第1期11卷 137-153页

作者： Zheng Shao Masashi nishimoto Izumi Muto Yu Sugawara Department of Materials Science Graduate School of EngineeringTohoku University6-6-02 Aza-AobaAramakiAoba-kuSendai 980-0579Japan

A model specimen with a single boundary of theα/βphase simulating Mg-Al alloys was successfully fabricated by spark plasma sintering.A small electrode area ofαphase orβphase was prepared using the model specimen,and the OCPs(open-circuit potentials)of each phase and a small electrode area containing theα/βphase boundary in 0.1 M NaCl at pH 8.0 were compared:theβphase exhibited a higher potential,and theαphase showed a lower *** OCP of the small area containing theα/βphase boundary was the intermediate value of these *** a small area containingα/βphase boundary,discoloration and gas bubbles were observed on theαphase,but no bubble generation was detected on theβ*** gas bubbles were initially generated on theαphase near theβphase,but as the discoloration(corrosion)of theαphase approached theβphase,the bubbles were generated on theβ*** micro-galvanic corrosion of theαandβphases,theβphase did not always function as the preferred ***αphase partially corroded(or discolored)and became the anodes,so that the surrounding areas were most likely to be the *** corroded areas(anodes)in theαphase approached theβphase,theβphase would become *** addition to the micro-galvanic corrosion mechanism,the role of Al in corrosion resistance at theα/βphase boundary was determined by surface analysis.

关键词： Magnesium alloy α/βphase boundary Micro-scale observation technique Micro-galvanic corrosion Spark plasma sintering

Thermal Properties of Al-50%Si Alloys

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材料热处理学报 2004年第5期25卷 180-182页

作者： Akio nishimoto Katsuya Akamatsu Kazuyoshi Nakao Kazuo Ichii Department of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka Japan

In order to prepare a hypereutectic Al-Si alloy with low coefficients of thermal expansion (CTE), Al-50%Si alloy was produced by powder metallurgy (P/M) and ingot metallurgy (I/M). P/M specimen was prepared by mechanical alloying (MA) and pulsed electric-current sintering (PECS). The microstructures of specimens were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Vickers microhardness and CTE measurements were performed. The grains in the P/M specimen were refined with increasing MA time. Primary Si and eutectic Si in the I/M specimen were remarkably refined by adding minute amounts of Sr. The CTE of P/M and I/M specimens were estimated as ***"6 and 10.7xlO"6, respectively. These values were as same as a CTE of AlaOs ceramics.

关键词： Al-Si合金热膨胀系数焙烧浇铸锶增加

Influence of Fine Sediment on the Fluidity of Debris Flows

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Journal of Mountain Science 2013年第2期10卷 233-238页

作者： Norifumi HOTTA Takahiro KANEKO Tomoyuki IWATA Haruo nishimoto Faculty of Life and Environmental Sciences University of Tsukuba3058577 IbarakiJapan Faculty of Agriculture The University of Tokyo1138657 TokyoJapan Graduate School of Agricultural and Life Sciences The University of Tokyo1138657 TokyoJapan

Debris flows include a great diversity of grain sizes with inherent features such as inverse grading, particle size segregation, and liquefaction of fine sediment. The liquefaction of fine sediment affects the fluidity of debris flows, although the behavior and influence of fine sediment in debris flows have not been examined sufficiently. This study used flume tests to detect the effect of fine sediment on the fluidity of laboratory debris flows consisting of particles with various diameters. From the experiments, the greatest sediment concentration and flow depth were observed in the debris flows mixed with fine sediment indicating increased flow resistance. The experimental friction coefficient was then compared with the theoretical friction coefficient derived by substituting the experimental values into the constitutive equations for debris flow. The theoretical friction coefficient was obtained from two models with different fine-sediment treatments： assuming that all of the fine sediments were solid particles or that the particles consisted of a fluid phase involving pore water liquefaction. From the comparison of the friction coefficients, a fully liquefaction state was detected for the fine particle mixture. When the mixing ratio and particle size of the fine sediment were different, some other eases were considered to be in a partially liquefied transition state. These results imply that the liquefaction of fine sediment in debris flows was induced not only by the geometric conditions such as particle sizes, but also by the flow conditions.

关键词： Debris flow Fine sediment Friction coefficient Liquefaction Open channel Reynolds stress

Preparation of Fe-Al Binary System Intermetallic Compounds by Multi-Layered Roll-Bonding

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材料热处理学报 2004年第5期25卷 53-55页

作者： Akio nishimoto Katsuya Akamatsu Kazuyoshi Nakao Kazuo Ichii Tomohiro Hiraki Department of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka JapanDepartment of Materials Science and Engineering Kansai University Osaka JapanToho Zinc Co. Ltd. Gunma Japan

Iron aluminides exhibit good resistance to high-temperature sulfidizing and oxidizing environments and potential for structural applications at high temperatures under corrosive environments. In this study, Fe-Al intermetallic compound was prepared by multi-layered roll-bonding of elemental Fe and Al foils. The process consisted of the accumulative roll-bonding (ARE) for making a laminated Fe/Al sheet and the subsequent heat treatment promoting a solid phase reaction in the laminated Fe/Al sheet. The microstructures produced at each processing stage were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Vickers microhardness testing was used for hardness determination. A homogeneous intermetallic compound of Fe3Al or FeAl could be obtained after the subsequent heat treatment for 1.8 ks at 973 K and for 10.8 ks at 1123 or 1173 K.

关键词：铁铝合金金属互化物辊压接合分界面反应反应扩散

The Process of Support by Nursing Professionals for Families Having a Member with Borderline Personality Disorder

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Open Journal of Nursing 2016年第1期6卷 24-36页

作者： Yasuyo nishimoto Naohiro Hohashi Division of Family Health Care Nursing Department of Nursing Graduate School of Health Sciences Kobe University Hyogo Japan

The purpose of this study was to explore the process of family support provided by nurses to families with a borderline personality disorder (BPD) patient. Semi-structured interviews were conducted with 16 nurses who had provided care to BPD patients. Data obtained from the interviews were qualitatively analyzed using a modified grounded theory approach. As an overall core category of family support processes practiced by nurses for families with BPD patients, family support practiced without awareness that the nurses were supporting families was extracted. Through this process, nurses held perceptions that were premises for family support, which were formed through their individual nursing experiences and perspectives. Nurses also had diverse perceptions concerning the image of families. Through the integration of perceptions that were premises for family support and perceptions of an image of the family, nurses underwent a process of “determination and ambivalence about the need for family support.” Then, nurses provided “family support practice” when they acknowledged the need for family support. During the “family support practice,” nurses had difficulties in providing family support. When family support was not successfully provided, nurses provided “family support practice with seeking more effective ways through trial and error.” For cases in which nurses did not acknowledge the need for intervention, they intentionally chose “not to provide family support.” Furthermore, during the “family support practice,” nurses had contradictory perspectives of family support. Such family support processes ultimately led to an awareness of the same family support required for the future. Family support was provided with “family support practice” and “family support practice with seeking more effective ways through trial and error.” In some cases, however, the process ended in “not to provide family support intentionally.” Experiences and perspectives in providing family s

关键词： Family Nursing Process of Family Support Borderline Personality Disorder (BPD) Modified Grounded Theory Approach (M-GTA)

Risk factors for small intestinal adenocarcinomas that are common in the proximal small intestine

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World Journal of Gastroenterology 2022年第39期28卷 5658-5665页

作者： Shunji Fujimori Ryohei Hamakubo Aitoshi Hoshimoto Takayoshi nishimoto Jun Omori Naohiko Akimoto Shu Tanaka Atsushi Tatsuguchi Katsuhiko Iwakiri Department of Gastroenterology Chiba Hokusoh HospitalNippon Medical SchoolChiba 270-1694Japan Department of Gastroenterology Nippon Medical SchoolGraduate School of MedicineTokyo 113-8603Japan Department of Gastroenterology Tama-Nagayama HospitalNippon Medical SchoolTokyo 206-0025Japan

The frequency of primary small intestinal adenocarcinoma is increasing but is still *** frequency is approximately 3%of that of colorectal *** that the small intestine occupies 90%of the surface area of the gastrointestinal tract,small intestinal adenocarcinoma is very *** main site of small intestinal adenocarcinoma is the proximal small *** on this characteristic,dietary animal proteins/lipids and bile concentrations are implicated and reported to be involved in *** most nutrients are absorbed in the proximal small intestine,the effect of absorbable intestinal content is a suitable explanation for why small intestinal adenocarcinoma is more common in the proximal small *** proportion of aerobic bacteria is high in the proximal small intestine,but the absolute number of bacteria is *** addition,the length and density of villi are greater in the proximal small ***,the involvement of villi is considered to be low because the number of small intestinal adenocarcinomas is much smaller than that of colorectal *** the other hand,the reason for the low incidence of small intestinal adenocarcinoma in the distal small intestine may be that immune organs reside *** and disease factors increase the likelihood of small intestinal *** carcinogenesis experiments in which the positions of the small and large intestines were exchanged,tumors still occurred in the large intestinal mucosa more *** other words,the influence of the intestinal contents is small,and there is a large difference in epithelial properties between the small intestine and the large *** conclusion,small intestinal adenocarcinoma is rare compared to large intestinal adenocarcinoma due to the nature of the *** is reasonable to assume that diet is a trigger for small intestinal adenocarcinoma.

关键词： Small intestine Large intestine Adenocarcinoma Risk factor Carcinogenesis

Benefits of endoscopic gallbladder stenting following percutaneous transhepatic gallbladder drainage

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World Journal of Gastrointestinal Surgery 2024年第9期16卷 2902-2909页

作者： Fumitaka Niiya Naoki Tamai Masataka Yamawaki Jun Noda Tetsushi Azami Yuichi Takano Fumiya nishimoto Masatsugu Nagahama Division of Gastroenterology Department of Internal MedicineShowa University Fujigaoka HospitalYokohama 227-8501KanagawaJapan

BACKGROUND Endoscopic transpapillary gallbladder drainage is challenging because of the complexity of the procedure and high incidence of adverse events(AEs).To overcome these problems,endoscopic gallbladder stenting(EGBS)after percutaneous transhepatic gallbladder drainage(PTGBD)can be effective,as it mitigates inflammation and *** To examine the benefits of EGBS after PTGBD to assess its efficacy and impact on *** We retrospectively analyzed data from 35 patients who underwent EGBS after PTGBD at a single center between January 2016 and December *** primary outcomes were technical success and AEs,and the rate of recurrent cholecystitis was *** addition,the reasons for the failure of the procedure were *** Among the 35 patients,the technical success rate was 77.1%and the final contrast of the cystic duct was successful in 97.1%of *** incidence of early AEs was relatively low(11.4%),with no instances of cystic duct *** rate of recurrent cholecystitis was 3.7%,and no other biliary events were *** EGBS after PTGBD may be significantly beneficial,with a substantial success rate and minimal AEs in both short-and long-term follow-ups.

关键词： Endoscopy Gallbladder Stents Drainage Adverse events Cholecystitis Follow-up Cystic duct