{"_buckets": {"deposit": "d491d6f0-26e1-4d17-a2cc-93b988fad3ee"}, "_deposit": {"created_by": 1, "id": "542", "owners": [1], "pid": {"revision_id": 0, "type": "depid", "value": "542"}, "status": "published"}, "_oai": {"id": "oai:ir.soken.ac.jp:00000542", "sets": ["12"]}, "author_link": ["0", "0", "0"], "item_1_biblio_info_21": {"attribute_name": "書誌情報（ソート用）", "attribute_value_mlt": [{"bibliographicIssueDates": {"bibliographicIssueDate": "2008-09-30", "bibliographicIssueDateType": "Issued"}, "bibliographic_titles": [{}]}]}, "item_1_creator_2": {"attribute_name": "著者名", "attribute_type": "creator", "attribute_value_mlt": [{"creatorNames": [{"creatorName": "徐, 祺"}], "nameIdentifiers": [{"nameIdentifier": "0", "nameIdentifierScheme": "WEKO"}]}]}, "item_1_creator_3": {"attribute_name": "フリガナ", "attribute_type": "creator", "attribute_value_mlt": [{"creatorNames": [{"creatorName": "シュウ, チィ"}], "nameIdentifiers": [{"nameIdentifier": "0", "nameIdentifierScheme": "WEKO"}]}]}, "item_1_date_granted_11": {"attribute_name": "学位授与年月日", "attribute_value_mlt": [{"subitem_dategranted": "2008-09-30"}]}, "item_1_degree_grantor_5": {"attribute_name": "学位授与機関", "attribute_value_mlt": [{"subitem_degreegrantor": [{"subitem_degreegrantor_name": "総合研究大学院大学"}]}]}, "item_1_degree_name_6": {"attribute_name": "学位名", "attribute_value_mlt": [{"subitem_degreename": "博士（工学）"}]}, "item_1_description_1": {"attribute_name": "ID", "attribute_value_mlt": [{"subitem_description": "2008511", "subitem_description_type": "Other"}]}, "item_1_description_12": {"attribute_name": "要旨", "attribute_value_mlt": [{"subitem_description": "　　　Development of breeding and structural materials for blankets is the key issue of fusion reactors. Fe-Cr-W based RAFM (Reduced Activation Ferritic/Martensite) steels are widely regarded as promising blanket structural materials, because of its low activation properties, radiation resistance and industrial maturity. Blanket concepts with liquid lithium (Li) breeder/coolant provide attractive options for high tritium breeding ratio, high efficiency and simplicity of blanket system. \u003cbr /\u003e　　　One of the critical issues for RAFM/Li blanket is the compatibility of RAFM steel\u003cbr /\u003ewith liquid Li. As to the corrosion of ferritic steels in Li, only studies on conventional\u003cbr /\u003eFe-Cr-Mo are available. In those studies, however, investigation on microstructure and\u003cbr /\u003emicro-chemical processes are quite limited. Any data are not available for RAFM\u003cbr /\u003e(Fe-Cr-W) steels yet. \u003cbr /\u003e　　　The purpose of the present study is to examine the compatibility of RAFM steels\u003cbr /\u003ewith liquid Li with respect to corrosion rate and the degradation of mechanical\u003cbr /\u003eproperties and to classify the underlying mechanism based on the element transfer and\u003cbr /\u003echange of microstructure during the corrosion process. \u003cbr /\u003e　　　In this study, the compatibility of JLF-1(Fe-9Cr-2W-0.1C), a RAFM steel\u003cbr /\u003edeveloped in Japan, with static and flowing Li was investigated. The coupon specimens\u003cbr /\u003e (16×4×0.25mm) were exposed in an isothermal pot for static tests and thermal\u003cbr /\u003econvection SS316 (Fe-Cr-Ni) loop for flowing tests. After exposure, the corrosion\u003cbr /\u003echaracteristics were examined by fine scale weight measurement, SEM/EDS (Scanning\u003cbr /\u003eElectron Microscope/Energy Dispersive X-ray Spectrometer), TEM (Transmission\u003cbr /\u003eElectron Microscopy) and Vickers hardness test. \u003cbr /\u003e　　　In the static test, the weight loss of JLF-1 specimens increased with temperature. \u003cbr /\u003eAfter exposure at 700°C for 100h, JLF-1 specimens suffered severe corrosion and the\u003cbr /\u003ecorrosion rate was 0.18mm/yr. The kinetics of weight loss at temperature of 500°C and\u003cbr /\u003e600 °C showed that the corrosion of JLF-1 became saturated with the exposure time. \u003cbr /\u003eThis is possibly due to the formation of saturated layer of dissolved elements in liquid\u003cbr /\u003elithium near the specimen surface. In the corrosion test in a thermal convection loop, the\u003cbr /\u003ecorrosion rate at 500°C for 250h was significantly larger than that obtained in the static\u003cbr /\u003etest in an identical condition. After Li exposure, the phase transformation from\u003cbr /\u003emartensite to ferrite was found on the samples. This is the first time that the phase\u003cbr /\u003echange from martensite to ferrite is observed after Li attack. The chemical analysis\u003cbr /\u003eresults and the depletion of carbides suggested that the phase change should be caused by the depletion of carbon. At the same time, selective depletion of other alloy elements, such as Cr and W, was detected by EDS on the surface. Vickers hardness results showed that obvious softening occurred on the surface of the specimens after Li exposure and the depth of the softened region was consistent with that of the phase transformation. \u003cbr /\u003eThe flowing Li enhanced the weight loss, phase change and reduction of hardness due\u003cbr /\u003eto the mass transfer effect. \u003cbr /\u003e　　　The influence of alloy composition on the corrosion was investigated by\u003cbr /\u003ecomparing the corrosion behavior of JLF-1, binary Fe-Cr and pure iron at 700°C for\u003cbr /\u003e100hr. The corrosion of JLF-1 is more significant than that of Fe-9Cr and pure iron at\u003cbr /\u003e973K. The selective dissolution of Cr, W and C into lithium seems to enhance the\u003cbr /\u003ecorrosion. Significant phase transformation from martensite to ferrite to the depth of\u003cbr /\u003e100μm was observed on the JLF-1 specimens after exposure in Li at 700°C for 100h. \u003cbr /\u003eThe phase change resulted in drastic hardness drop from 250 to 140Hv. For the Fe-9Cr, \u003cbr /\u003ethe softened layer (～5μm) was found on the surface of the specimen after Li attack due\u003cbr /\u003eto the depletion of Cr and W. This was verified by the EDS line scan on the cross\u003cbr /\u003esection of specimens. No mechanical change was observed on the pure Fe specimen\u003cbr /\u003ebefore and after exposure. \u003cbr /\u003e　　　To study the influence of container materials, the coupon specimens of JLF-1 were\u003cbr /\u003eexposed in Mo, SS316 and Nb crucibles separately at 600°C for 250h. The corrosion\u003cbr /\u003echaracteristics in different crucible were compared. After exposure, the specimens\u003cbr /\u003eexposed in Mo and Nb crucible lost weight, while the specimens in SS316 crucible\u003cbr /\u003egained weight due to the precipitation of Ni dissolved from crucible materials. The\u003cbr /\u003ephase transformation was observed on cross section of specimens exposed in Nb\u003cbr /\u003ecrucible (～20μm) and Mo crucible (～10μm). No phase change was found in the case of\u003cbr  /\u003eSS316 container. The phase change caused a corresponding reduction of hardness on\u003cbr /\u003eJLF-1 samples in depth. It is clear that the Nb container enhanced the depletion of\u003cbr /\u003ecarbon and the phase transformation by trapping C and achieving a very low C\u003cbr /\u003econcentration in Li.\u003cbr /\u003e　　　Analysis of the experimental results was carried out based on the thermodynamic\u003cbr /\u003eand kinetic modeling. The results showed that the driving force of corrosion is the level\u003cbr /\u003eof Fe and Cr in Li. Saturation of those elements in Li results in the suppression of\u003cbr /\u003ecorrosion. However, production of compounds of N, Li and alloy elements was shown\u003cbr /\u003eto determine the level of Fe and Cr in Li. The loss of C leads to the phase change. The\u003cbr /\u003edriving force of decarburization is the level of C in Li. The trapping of C by the\u003cbr /\u003econtainer materials can enhance the phase transformation. The diffusion of C in the\u003cbr /\u003emartensite controls the extension of phase change region.\u003cbr /\u003e　　　In conclusion, expected influences of Li attack to RAFM steel are the loss of\u003cbr /\u003ematerials by dissolution of the constituent elements and the degradation of mechanical\u003cbr /\u003eproperties caused by phase transformation from martensite to ferrite as the result of dissolution of C. Based on the data obtained, the compatibility of RAFM steel in Li\u003cbr /\u003eseems not to be a serious issue once the level of N in Li is kept low. The phase\u003cbr /\u003etransformation will be reduced by avoiding the use of materials which has high affinity\u003cbr /\u003ewith C.", "subitem_description_type": "Other"}]}, "item_1_description_7": {"attribute_name": "学位記番号", "attribute_value_mlt": [{"subitem_description": "総研大甲第1192号", "subitem_description_type": "Other"}]}, "item_1_select_14": {"attribute_name": "所蔵", "attribute_value_mlt": [{"subitem_select_item": "有"}]}, "item_1_select_8": {"attribute_name": "研究科", "attribute_value_mlt": [{"subitem_select_item": "物理科学研究科"}]}, "item_1_select_9": {"attribute_name": "専攻", "attribute_value_mlt": [{"subitem_select_item": "10 核融合科学専攻"}]}, "item_1_text_10": {"attribute_name": "学位授与年度", "attribute_value_mlt": [{"subitem_text_value": "2008"}]}, "item_creator": {"attribute_name": "著者", "attribute_type": "creator", "attribute_value_mlt": [{"creatorNames": [{"creatorName": "XU, Qi", "creatorNameLang": "en"}], "nameIdentifiers": [{"nameIdentifier": "0", "nameIdentifierScheme": "WEKO"}]}]}, "item_files": {"attribute_name": "ファイル情報", "attribute_type": "file", "attribute_value_mlt": [{"accessrole": "open_date", "date": [{"dateType": "Available", "dateValue": "2016-02-17"}], "displaytype": "simple", "download_preview_message": "", "file_order": 0, "filename": "甲1192_要旨.pdf", "filesize": [{"value": "336.3 kB"}], "format": "application/pdf", "future_date_message": "", "is_thumbnail": false, "licensetype": "license_11", "mimetype": "application/pdf", "size": 336300.0, "url": {"label": "要旨・審査要旨", "url": "https://ir.soken.ac.jp/record/542/files/甲1192_要旨.pdf"}, "version_id": "c2e338dc-aa55-42d3-96f7-5b217a940b4a"}, {"accessrole": "open_date", "date": [{"dateType": "Available", "dateValue": "2016-02-17"}], "displaytype": "simple", "download_preview_message": "", "file_order": 1, "filename": "甲1192_本文.pdf", "filesize": [{"value": "6.6 MB"}], "format": "application/pdf", "future_date_message": "", "is_thumbnail": false, "licensetype": "license_11", "mimetype": "application/pdf", "size": 6600000.0, "url": {"label": "本文", "url": "https://ir.soken.ac.jp/record/542/files/甲1192_本文.pdf"}, "version_id": "f9186d61-07d2-49e6-86cd-04d304e82796"}]}, "item_language": {"attribute_name": "言語", "attribute_value_mlt": [{"subitem_language": "eng"}]}, "item_resource_type": {"attribute_name": "資源タイプ", "attribute_value_mlt": [{"resourcetype": "thesis", "resourceuri": "http://purl.org/coar/resource_type/c_46ec"}]}, "item_title": "Compatibility of Reduced Activation Ferritic/Martensitic Steel with Liquid Lithium", "item_titles": {"attribute_name": "タイトル", "attribute_value_mlt": [{"subitem_title": "Compatibility of Reduced Activation Ferritic/Martensitic Steel with Liquid Lithium"}, {"subitem_title": "Compatibility of Reduced Activation Ferritic/Martensitic Steel with Liquid Lithium", "subitem_title_language": "en"}]}, "item_type_id": "1", "owner": "1", "path": ["12"], "permalink_uri": "https://ir.soken.ac.jp/records/542", "pubdate": {"attribute_name": "公開日", "attribute_value": "2010-02-22"}, "publish_date": "2010-02-22", "publish_status": "0", "recid": "542", "relation": {}, "relation_version_is_last": true, "title": ["Compatibility of Reduced Activation Ferritic/Martensitic Steel with Liquid Lithium"], "weko_shared_id": 1}