Y添加量对齿轮用真空感应熔炼ZK60合金组织及拉伸性能的影响

通过真空感应熔炼并结合快速冷却的方法制得齿轮用ZK60镁合金,分析Y添加量对其微观组织及拉伸性能的影响。研究结果表明:真空感应熔炼ZK60合金获得了细小组织,α-Mg晶粒都是以尺寸较小的枝晶结构存在,晶粒外径尺寸减小到了26μm以内。真空感应熔炼过程也会产生晶粒细化效果,使合金内形成更低比例的β相。Y加入量至1%,得到的合金基体内形成了更细的晶粒。此时真空感应熔炼ZK60合金形成了更大的晶粒,达到18.1μm。当枝晶不断长大后可以对含Al液相起到连接的作用,得到具有网状结构的β-Mg₁₇Al₁₂相。随着Y添加量的增加,真空感应熔炼ZK60合金的拉伸强度和延伸率均表现出先增加后减小,最大值发生在最佳含量Y为1%时,此时拉伸强度和延伸率分别取值为378 MPa和11.26%。

Property Modification of ZK60 Al-Mg Alloy by Y-Doping

The properties of ZK60 Al-Mg alloy,an advanced gear material for aircraft engine and produced by vacuum induction melting combined with rapid solidification,were modified by doping of yitrium.The influence of the Y-doping on the microstructures and tensile properties was investigated with X-ray diffraction,scanning electron microscopy and tensile behavior measurement.The results show that the Y-doping had a major impact.To be specific,as the Y-content increased,the tensile strength and elongation ratio changed in an increase-decrease mode,maximizing to 378 MPa and 1.26%,respective,at 1%(wt)Y.Addition of 1.0% Y resulted in the formation of a large amount of finer equiaxed grains,coexisting with the fairly large dendrite α-Mg grains(18.1 μm in size).We found that the growth of the dendrite α-Mg grains were responsible for the formation of β-Mg₁₇Al₁₂-phased reticular framework.