1994 Fiscal Year Final Research Report Summary
DEVELOPMENT OF MOLYBDENUM ALLOYS WITH IMPROVED TOUGHNESS BY MECHANICAL ALLOYING
| Project/Area Number |
04452267
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
KURISHITA Hiroaki TOHOKU UNIVERSITY,INSTITUTE FOR MATERIALS RESEARCH,ASSOCIATE PROFESSOR, 金属材料研究所, 助教授 (50112298)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAOKA Yutaka OKAYAMA UNIVERSITY OF SCIENCE,DEPARTMENT OF APPLIED PHYSICS,PROFESSOR, 理学部・応用物理, 教授 (70228774)
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| Project Period (FY) |
1992 – 1994
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| Keywords | MOLYBDENM / TRANSITION METAL CARBIDE / MECHANICAL ALLOYING / TOUGHNESS / RECRYSTALLIZATION / IRRADIATION / EMBRITTLEMENT / HIGH TEMPERATURE STRENGTH |
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| Research Abstract |
We have successfully developed molybdenum alloys with the aimed properties by applying mechanical alloying and hot isostatic pressing treatment to mixed powders of pure molybdenm and transitional metal carbides (TiC or HfC). The developed alloys exhibit much improved toughness at low temperatures, much improved resistance to recrystallization and grain growth, much improved resistance to radiation embrittlement, and much improved strength at high temperatures than TZM alloy which is currently most widely used among the commerially available molybdenum alloys. TEM observation has showed that the characteristic of microstructures of the developed alloys in the as-rolled state is extremely small grain size ranging from 10 to 400 nm, a high density of dislocations and a large number of very fine carbide particles mostly existing at grain boundaries. It has also been shown that such microstructues are very resistant to the detrimental effect of oxygen impurity, however, reducing the amount of oxygen may allow to further improve the properties of the developed alloys, which is now in progress. In addition, we are planning on developing tungsten alloys having improved low-temperature toughness and improved resistance to recrystallization and radiation embrittlement, because tugsten has the highest melting point among metals, but its use is severely impaired by the intergranular embrittleness at ambient temperature.
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