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利用等离子体发射光谱仪(ICP)、光学显微镜(OM)、扫描电子显微镜(SEM)等分析手段研究了Mg-x Zn-y Gd(x=1~3,y=1~3)合金铸造态、挤压态的化学成分和微观组织演变,并测试其室温拉伸力学性能。研究结果表明:随着Gd含量的增加,铸态组织显著细化,枝状晶间距减小,其组分相Mg-Zn-Gd三元相面积分数逐渐增多,Mg Zn2相逐渐减少直至消失,第二相从晶界处呈连续网状分布转变成晶界断续和晶内均匀分布。挤压态组织得到细化,挤压过程发生了明显的动态再结晶,平均晶粒尺寸从Mg-3Zn合金的30μm降到Mg-2Zn-1Gd合金的10μm。第二相沿挤压方向趋于带状分布,部分弥散分布于晶内,成棒状或块状的Mg Zn Gd三元相,尺寸约为1~3μm。挤压态Mg-x Zn-y Gd合金的抗拉强度σ_b从Mg-3Zn的260 MPa提高到300 MPa,延伸率δ从13%提高到25%,屈服强度变化不大,σ_b和δ提高幅度分别为15.4%,92%。挤压态的显微硬度由Mg-3Zn的HV 52.1提高到Mg-3Zn-2Gd的HV 70.4,挤压态Mg-x Zn-y Gd合金室温拉伸断口呈现典型的韧性断裂特征,应力在第二相粒子处集中。
The casting conditions of Mg-x Zn-y Gd (x = 1 ~ 3, y = 1 ~ 3) alloys were studied by means of ICP, OM and SEM. Squeeze the chemical composition and microstructure evolution, and test its tensile properties at room temperature. The results show that with the increase of Gd content, the as-cast microstructure is refined and the dendrite spacing is decreased. The area fraction of Mg-Zn-Gd ternary phase increases gradually and the Mg-Zn2 phase decreases until it disappears. The second phase changes from the continuous reticular distribution at the grain boundaries to the intermittent and uniform distribution in the grain boundaries. Extruded microstructure was refined, and the dynamic recrystallization occurred obviously during extrusion. The average grain size decreased from 30μm in Mg-3Zn alloy to 10μm in Mg-2Zn-1Gd alloy. The second phase tends to strip distribution along the extrusion direction, partially dispersed in the crystal and formed into a rod-shaped or massive Mg Zn Gd ternary phase with a size of about 1-3 μm. The tensile strength σ_b of extruded Mg-xZn-yGd alloy increased from 260 MPa to 300 MPa of Mg-3Zn, the elongation δ increased from 13% to 25%, the yield strength did not change much, and the increases of σ_b and δ Respectively 15.4%, 92%. The microhardness of extruded Mg-3Zn alloy increases from HV52.1 of Mg-3Zn to HV70.4 of Mg-3Zn-2Gd. The tensile fracture of extruded Mg-xZn-yGd alloy exhibits typical ductile fracture at room temperature. Two-phase particles at the concentration.