Effect of Zn addition on microstructure and mechanical properties of cast Mg-Gd-Y-Zr alloys

Authors

Zhibing Ding, North University of China
Yuhong Zhao, North University of China
Ruopeng Lu, North University of China
Mei-Ni Yuan, North University of China
Zhijun Wang, North University of China
Hui Jun Li, University of WollongongFollow
Hua Hou, North University of China

RIS ID

135420

Publication Details

Ding, Z., Zhao, Y., Lu, R., Yuan, M., Wang, Z., Li, H. & Hou, H. (2019). Effect of Zn addition on microstructure and mechanical properties of cast Mg-Gd-Y-Zr alloys. Transactions of Nonferrous Metals Society of China, 29 (4), 722-734.

Abstract

The effects of Zn addition on the microstructure and mechanical properties of Mg-10Gd-3Y-0.6Zr (wt.%)alloys in the as-cast, solution-treated, and peak-aged conditions were investigated. Experimental results reveal that the microstructure of the as-cast alloy without Zn consists of α-Mg and Mg 24 (Gd,Y) 5 phases, and the alloy with 0.5 wt.% Zn consists of α-Mg, (Mg,Zn) 3 (Gd,Y)and Mg 24 (Gd,Y,Zn) 5 phases. With the addition of Zn increasing to 1 wt.%, the Mg 24 (Gd,Y,Zn) 5 phase disappears and some needle-like stacking faults distribute along the grain boundaries. Moreover, the 18R long-period stacking ordered (LPSO)phase is observed in the as-cast alloy with 2 wt.% Zn. After solution treatment, the Mg 24 (Gd,Y) 5 and Mg 24 (Gd,Y,Zn) 5 eutectic phases are completely dissolved, and the (Mg,Zn) 3 (Gd,Y)phase, needle-like stacking faults and 18R LPSO phase all transform into 14H LPSO phase. Both the suitable volume fraction of 14H LPSO phases and the fine ellipsoidal-shaped β′ phases make the peak-aged alloy with 0.5 wt.% Zn exhibit excellent comprehensive mechanical properties and the UTS, YS and elongation are 338 MPa, 201 MPa and 6.8%, respectively.