钇对Mg-12Gd-1Zn-0.6Zr镁合金组织和性能的影响

Influences of Y on the microstructures and mechanical properties of Mg-12Gd-1Zn-0.6Zr magnesium alloys

为加强Mg-Gd-Y基高强镁合金的开发,拓展镁合金的应用,采用金相显微镜、扫描电镜、X射线衍射、差热分析和拉伸试验等手段,研究了Y对Mg-12Gd-1Zn-0.6Zr镁合金组织和性能的影响。结果表明:在Mg-12Gd-1Zn-0.6Zr镁合金中,Y添加的质量分数为2%时对合金铸态组织的影响不大;当添加3%和4%会导致合金铸态组织粗化,并使合金组织中的第二相由不连续分布的细小网状变成粗大的骨骼状;添加2%～4%还可使合金挤压后的晶粒细化,其中添加2%和3%较添加4%获得更好的细化效果。此外,添加2%～4%可明显提高合金挤压后的抗拉强度和屈服强度,其中添加2%可使合金挤压后的抗拉强度、屈服强度和延伸率分别达到348.8MPa、256.8MPa和14.7%。

To develop Mg-Gd-Y based high-strength alloys and widen the application of magnesium alloys, the effects of Y addition on the microstructure and mechanical properties of Mg-12Gd-1Zn-0.6Zr alloy are investigated by using both optical and electron microscopy, X-ray diffraction （XRD）, differential scanning calorimetric （DSC） analysis,and tensile test. The results indicate that adding 2%Y to the Mg-12Gd-1Zn-0.6Zr alloy does not cause an obvious change in the as-cast microstructure of the alloy. However, after adding 3% and 4% Y, the as-cast microstructure of the alloy is coarsened,and simultaneously the morphology of the secondary phases in the alloy is changed from the initial discontinuous fine network to thick skeleton-like frame. Furthermore, adding 2 %-4%Y to the Mg-12Gd-1Zn-0. 6Zr alloy can also refine the grains of the as-extruded alloy, and adding 2%and 3% Y can obtain higher refining efficiency than adding 4%Y. In addition,adding 2%-4% Y to the Mg-12Gd-1Zn-0.6Zr alloy can also effectively improve the ultimate tensile strength and yield strength of the as-extruded alloy, and the ultimate tensile strength, yield strength and elongation of the as-extruded alloy with the addition of 2% Y can reach 348.8 MPa,256.8 MPa and 14.7% ,respectively.