1997 Fiscal Year Final Research Report Summary
POWDER PRODUCTION BY HYDROGEN PULVERIZATION OF FUNCTIONAL INTERMETALLICS AND DEVELOPMENT OF CLOSED SYSTEM FOR POWDER CONSOLIDATION
| Project/Area Number |
07555509
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
HANADA Shuji TOHOKU UNIVERSITY,INSTITUTE FOR MATERIALS RESERACH,PROFESSOR, 金属材料研究所, 教授 (10005960)
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| Co-Investigator(Kenkyū-buntansha) |
MURAHASHI Noriaki MITSUBISHI MATERIRALS,CENTRAL RESEARCH INSTITUTIE,RESERACHER, 中央研究所, 研究員
KONO Toru MITSUBISHI MATERIRALS,CENTRAL RESEARCH INSTITUTIE,VICE DIRECTOR, 中央研究所, 副所長
YOSHIMI Kyosuke TOHOKU UNIVERSITY,INSTITUTE FOR MATERIALS RESERACH,RESEARCH ASSOCIATE, 金属材料研究所, 助手 (80230803)
MURAYAMA Yonosuke TOHOKU UNIVERSITY,INSTITUTE FOR MATERIALS RESERACH,RESEARCH ASSOCIATE, 金属材料研究所, 助手 (60111308)
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| Project Period (FY) |
1995 – 1997
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| Keywords | intermetallic compound / hydrogen absorbing alloy / pulverization / pressure-hydrogen content-isotherm / microstructure control / powder metallurgy process |
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| Research Abstract |
In order to develop a powder production process of structural intermetallics via hydrogen pulverization and to improve cycling lifetime of hydrogen absorption and desorption in hydrogen absorbing intermetallics, hydrogen pulverization mechanisms have been investigated using Nb_3Al and NbCr_2 base intermetallic alloys. Since the ability of hydrogen absorption is sensitive to the surface oxide film covering intermetallics, all samples were prepared without exposing to air in a specially designed closed system. In this system a glove box is attached to a vacuum furnace. Hydrogen absorption-desorption curves were measured, lattice constants were calculated before and after hydrogenation, and shape and size of pulverized particles were observed by optical and scanning electron microscopy. In Nb-Al binary alloys pulverization occurs only in two phase alloys, Nb_3Al/Nb and Nb_3Al/Nb_2AI.Monolithic Nb_3AI, Nb_2A1 and Nb are not pulverized, although they can absorb a considerable amount of hydrogen. In Nb-Cr binary alloys, only Nb solid solution can absorb hydrogen among constituent phases, Nb, NbCr_2, and Cr. Pulverization takes place only in Nb/NbCr_2 two phase alloys. When NbCr_2 is alloyed with Ti, it can absorb hydrogen. Ti-containing monolithic NbCr_2 is pulverized by hydrogenation. From these results, it is concluded that pulverization is initiated at a crack in an intermetallic compound which is caused by difference in dilatation either of both phases accompanied with hydrogen absorption or of surface and interior generated by a gradient of hydrogen content.
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