Effects of Cu addition on microstructure and mechanical properties of Er-modified Al-10Mg2Si cast alloys

作者：Wu Xiao-feng; Wang Zhen-cheng; Cheng Ting; Wang Ke-yan; Xiang Jun; Zhao Rong-da; Chen Shun-hua; Wu Fu-fa^*

来源：Journal of Central South University, 2022, 29(3): 795-806.

DOI：10.1007/s11771-022-4963-3

• Al-Mg2Si alloy
• Cu
• Er
• eutectic Mg2Si
• mechanical properties

The solidification microstructure and mechanical properties of hypoeutectic Al-10Mg(2)Si cast alloys with different Cu contents and 0.45 wt.% Er were investigated using an optical microscope, scanning electron microscope, and an electronic universal testing machine. Results showed that Cu and Er could significantly reduce the grain size of the eutectic Mg2Si phase from 15.4 mu m for the base alloy to 5.8 mu m for the alloy with 1.5 wt.% Cu and 0.45 wt.% Er. Meanwhile, the needle-like beta-Al5FeSi phase was modified to fine sized irregular shaped Cu, Er and Fe-rich particles with the additions of Cu and Er. The strength and ductility of the Al-10Mg(2)Si as-cast alloys were simultaneously improved by the additions of Cu and Er, and the ultimate tensile strength, yield strength and elongation increase from 223 MPa, 136 MPa and 2.1% to 337 MPa, 169 MPa and 4.7%, respectively. The heterogeneous nucleation of Mg2Si on AlP was avoided by forming Cu, Er and P-containing phases, due to the additions of Cu and Er. Moreover, the Cu and Er atomic clusters and their intermetallic segregated on the surface of the eutectic Mg2Si and inhibited the growth of the eutectic Mg2Si, which were responsible for the modification of the eutectic Mg2Si.