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| Microstructure of Al - Zn strengthened by - Mg - Cu aluminum alloy yttrium element |
| School of Malerial Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract The effects of yttrium on the microstructure of as-cast and post uniform treatment of aluminum alloys are studied in detail when yttrium is added into the melt in the form of aluminum-yttrium interalloy in the range of 0 -0.30%. When the adding amount of yttrium is 0.25% , the grain size of α（Al） is refined from 60 -70 μm to 40 -50 μm. Meanwhile the secondary dendrite space is decreased. The main equilibrium phases distributed at the grain boundary are determined as T（AlZnMgCu） and Y -containing phases. After 450 ℃ , 12 hours uniform heat treatment the grain boundary is no longer continuous. The educts exhibit as dot and strip. For 0.25% Y -7055 aluminum alloy the grain boundary is not coarse and apparent as before. There are yttrium containing phases（Al3Y and Al2Y） with 2 -3 μm size at the grain boundary and intracrystalline, which are beneficial to improve the property of aluminum alloy.
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2010, Vol. 31 
