| Project/Area Number |
03650579
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属材料(含表面処理・腐食防食)
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| Research Institution | Fukuoka University of Education |
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Principal Investigator |
FURUKAWA Minoru Fukuoka Univ. of Edu.Associate Professor, 教育学部, 助教授 (90112276)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1991: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Chill-cast / Al-Li-Zr alloy / Split aging / Positive temperature dependence of yield stress / delta'(Al_3Li) / bata'(Al_3Zr) / TEM observation / Deformation mechanism / δ^1(Al_3Li)-Li_2規則相 / B^1(Al_3Zr)-Li_2規則相 / AlーLiーZr合金 / δ'(Al_3Li)ーL1_2規則相 / β'(Al_3Zr)ーL1_2規則相 |
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| Research Abstract |
Experimental studies were made on split-age hardening and temperature dependence of yield stress in the chill cast Al-Li-Zr alloys.Results are as follows.
1.Chill cast condition:It is possible to dissolve lmass% Zr in Al by chill casting in a water colled copper mold of 3mm gap.
2.Optimum heat treatment condition : The first stage aging at 673K for 1.08x10^6s and the successively second stage aging at 473K for 1.08x10^4s provides a rather increase in the yield stress of chill cast Al-Li-Zr alloys than that by aging only at 473K.
3.Temperature dependence of yield stress : The binary Al-Li alloys aged to its peak strength show positive temperature dependence of yield stress. On the other hand,the yield stress of binary Al-Zr alloys decreases monotonically with increasing temperature. With increasing the Zr content of Al-Li-Zr alloy,the negative temperature dependence of the yield stress becomes apparent.
4.Observation of strain-induced dislocations by transmission electron microscopy: Dislocations move in pairs cutting through the delta'-Al_3Li particles during deformation at the temperature range showing positive temperature dependence of yield strength in the binary Al_3-Li alloys.Dislocations in the binary Al-Zr alloys by-pass,cross slip or climb over the beta'precipitates in the Al-Li-Zr alloys promote the cross slipping or climing over of dislocations and then make the alloy to deform more easily at elevated temperature.
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