Zn添加对铸造Mg-Gd-Y-Zr合金组织和力学性能的影响（英文）

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

研究Zn添加对Mg-10Gd-3Y-0.6Zr(wt.%)合金在铸态、固溶态和峰时效态下显微组织和力学性能的影响。实验结果表明,不含Zn的铸态合金由α-Mg和Mg_(24)(Gd,Y)_5相组成,而含0.5wt.%Zn的铸态合金由α-Mg、(Mg,Zn)_3(Gd,Y)和Mg_(24)(Gd,Y,Zn)_5相组成。随着Zn含量增加到1 wt.%,Mg_(24)(Gd,Y,Zn)_5相消失,一些针状堆垛层错沿晶界分布。此外,在含2wt.%Zn的铸态合金中观察到18R型长周期结构相。固溶处理后,Mg_(24)(Gd,Y)_5和Mg_(24)(Gd,Y,Zn)_5共晶相完全溶解,(Mg,Zn)_3(Gd,Y)相、针状堆垛层错和18R型长周期结构相均转化为14H型长周期结构相。适当体积分数的14H型长周期结构相和细小的椭球状β′相共同赋予峰时效态下含0.5 wt.%Zn合金优良的综合力学性能,该合金的抗拉强度、屈服强度和伸长率分别为338 MPa、201 MPa和6.8%。

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 ofα-Mg and Mg24(Gd,Y)5 phases,and the alloy with 0.5 wt.%Zn consists ofα-Mg,(Mg,Zn)3(Gd,Y)and Mg24(Gd,Y,Zn)5 phases.With the addition of Zn increasing to 1 wt.%,the Mg24(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 Mg24(Gd,Y)5 and Mg24(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-shapedβ′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.