Effect of Erbium on Precipitation of Aged Al-Zn-Mg-Cu-Li Alloy
0.3%Er is added to Al-5.6Zn-1.9Mg-1.6Cu-1.0Li alloy (in wt.%) to investigate the effect of erbium on microstructure of the alloy. Most of erbium exists in the primary Al3Er phases which are incoherent with the alloy matrix unevenly. A few of fine Al3Er phases, precipitated from supersaturated solid solution, are coherent with the matrix. η′-MgZn2 precipitates in the single-aged alloy are sparser than that in the double-aged alloy. A few of fine Al3Er phases act as the heterogeneous sites of η phases. There exist some precipitation free zones in the matrix around fine Al3Er precipitates. Erbium is segregated to grain boundary seriously. A few of Al3Er phases are present in grain boundary. The grain boundary precipitates are not continuous about the Al3Er phases.
Zhong Cao, Lixian Sun, Xueqiang Cao, Yinghe He
Z. K. Zhao et al., "Effect of Erbium on Precipitation of Aged Al-Zn-Mg-Cu-Li Alloy", Advanced Materials Research, Vols. 233-235, pp. 2193-2196, 2011