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The Study Of Trace Sc And Heat Treatment On Microstructure And Properties Of Al-zn-mg-cu-zr Aluminum Alloy

Posted on:2006-09-22Degree:MasterType:Thesis
Country:ChinaCandidate:G Q HuFull Text:PDF
GTID:2191360182968993Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
The effects of minor Sc/Zr and heat treatment on microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr alloy were studied in this paper by means of OM.TEM and SEM. The mechanism of above effects was analyzed. Results of the study are as follows:1. Additional of minor Sc to 3# alloy Al-7.60Zn-2.30Mg-1.30Cu-0.15Zr leads to the precipitation of secondary Al3(Sc, Zr) particles during solidification, which have a powerful grain refining effect, so the cast grain size of alloy 3# is apparently refined and the even grain size is about 20-30um.2. The minor Sc and Zr in 3# alloy Al-7.60Zn-2.30Mg-1.30Cu-0.30Sc-0.15Zr leads to the precipitation of secondary Al3(Sc, Zr) particles during homogenization, which have a powerful effect on pinning up the dislocations and grain boundaries, preventing the grain boundary migration, so the recrystallization temperature is elevated apparently.3. Due to additional of minor Sc(0.3wt%) , the mechanical properties of alloy 3# is fine than alloy 1# (Al-7.20Zn-1.90Mg-1.26Cu-0.13Zr) by T6(120℃×24h): the σb, σ0.2, δ are increased by 65MPa, 67MPa, 1.0% respectively.4. When the single aging system is T6(120℃×24h), the best mechanical properties and its solution treatment of alloy 2#( 0.16wt%Sc ,Al-7.50Zn-2.11Mg-1.28Cu-0.16Zr ) is concluded as follows: 470℃×2h.5. The effects of three different aging treaments T6, T 76 or T73, and RRA on mechanical properties of 2# alloy show that the best mechanical properties of 2# alloy is σb=643 MPa, σ0.2=577MPa, δ=10.7%, and the corresponding aging treatment is 470℃×120min; 120℃×24h (T6)。...
Keywords/Search Tags:Additional Sc of high strength aluminum alloy, heat treatment, mechanical properties, retrogression and raging(RRA)
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