生物医用Mg-6Zn-xGd合金的组织与力学性能

Microstructures and Mechanical Properties of Biomedical Mg-6Zn-xGd Alloys

通过OM、SEM和XRD研究了Mg-6Zn-xGd（x=0-4）合金的铸态和挤压态组织，测试了其室温拉伸力学性能。结果表明：随着Gd含量的增加，铸态组织逐渐细化，二次枝晶臂间距明显减小，生成的Mg-Zn-Gd新相逐渐增多，而MgZn2相逐渐减少直至完全消失，第二相趋于连续网状分布于晶界处；挤压态组织明显细化，平均晶粒尺寸从Mg．6Zn合金的12μm逐渐减至Mg-6Zn-3．41Gd合金的2μm。随着Gd含量的增加，铸态抗拉强度ob、屈服强度on2和伸长率6先分别从Mg．6Zn合金的154MPa、67MPa、6．5％增至Mg-6Zn-0，66Gd合金的215MPa、78MPa、13％，接着逐渐降低。挤压态拉伸力学性能明显提高，ob和。眈分别从Mg．6Zn合金的295MPa和193MPa逐渐增至Mg．6Zn，3．41Gd合余的350MPa和325Ⅷa．6先降低后提高．日均不低于10％．

Microstructures and mechanical properties of as-cast and extruded Mg-6Zn-xGd （x=0--4） alloys were investigated by OM, SEM and XRD. Meanwhile, the tensile mechanical property was tested at ambient temperature. The results show that as-cast microstructure is refined gradually with increasing the Gd content, where the space of second dendrite arm decreases obviously. Mg-Zn-Gd new phase increases gradually, while MgZn2 phase decreases gradually until to disappear completely. The second phase tends to distribute along grain boundary by continuous reticulation. Extruded microstructure is refined obviously, where the average grain size decreases from 12 mm for Mg-6Zn alloy to 2 mm for Mg-6Zn-3.41Gd alloy. With the increase of Gd content, tensile strength δb, yield strength-0.2 and elongation 8 first increases from 154 MPa, 67 MPa and 6.5% for as-cast Mg-6Zn alloy to 215 MPa, 78 MPa and 13% for as-cast Mg-6Zn-0.66Gd alloy, respectively, and then decreases gradually. Extruded tensile mechanical property is enhanced obviously. δb and δ0.2 increases gradually from 295 MPa and 193 MPa for Mg-6Zn alloy to 350 MPa and 325 MPa for Mg-6Zn-3.41Gd alloy, 8 first decreases, and then increases, which is not lower than 10%.