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.
李桂荣, 赵玉涛, 李季, 王宏明, 陈刚. 稀土钇强化Al—Zn—Mg—Cu铝合金的组织特征[J]. 江苏大学学报（自然科学版）, 2010, 31(1): 49-52.
Li Guirong, Zhao Yutao, LI Ji, Wang Hongming, Chen Gang. Microstructure of Al - Zn strengthened by - Mg - Cu aluminum alloy yttrium element[J]. Journal of Jiangsu University(Natural Science Eidtion)
, 2010, 31(1): 49-52.
2010, Vol. 31 
