稀土Y对Mg-6Zn-1Mn合金显微组织和力学性能的影响

Effect of Y addition on the microstructure and mechanical properties of Mg-6Zn-1Mn magnesium alloy

利用光学显微镜、X射线衍射仪、扫描电子显微镜、万能力学试验机等手段,系统研究了不同含量Y（1%-6%（质量分数））对Mg-6Zn-1Mn合金显微组织和力学性能的影响。结果表明,随着Y的不断增加,Mg-6Zn-1Mn系铸态合金主要物相演变规律为α-Mg＋Mg7Zn3→α-Mg＋I→α-Mg＋W→α-Mg＋X,这主要归因于不同的Zn/Y原子比。研究发现,当Y含量低于2%时,挤压可使晶界和晶粒内部析出细小弥散的第二相,同时提高了合金强度和室温延展性。而随着Y的进一步增加,第二相颗粒变大,且主要存在于晶界,热挤压过程中晶粒不易被挤碎,弱化了析出相与基体的界面能,最终使得挤压态合金综合力学性能降低。

The microstructure and mechanical properties of Mg-6Zn-1Mn magnesium alloy with different Y con-tent were investigated by OM,XRD and tensile testing,respectively.It was found that the phase evolution with the Y content of as-cast ZM61 magnesium alloys wasα-Mg＋ Mg7Zn3→α-Mg＋I→α-Mg＋W→α-Mg＋X,which is mainly attributed to the different atomic ratio of Zn/Y.when the Y content was lower than 2%,the extruded ZM6 1 magnesium alloys show a high strength and good ductility due to the precipitation of fine second phase under extrusion.In addition,dimple size is larger from the fracture surface.With the incensement of Y,the sec-ond phase particles,mainly precipiting on the grain boundary,become larger,which is difficult to be crushed and refined under the hot extrusion process.Therefore,the comprehensive mechanical properties of extruded al-loys decrease due to the weakening interfacial energy of the precipitates and matrix.