稀土Ce和Y对AZ80镁合金组织和力学性能的影响Effects of rare-earth Ce and Y on microstructure and mechanical properties of AZ80 Mg alloys

通过元素分析、性能测试、XRD、SEM和TEM等手段分析了稀土Ce和Y对AZ80镁合金熔炼、组织和力学性能的影响规律。结果表明：在AZ80合金熔炼过程中，添加稀土Y元素能够起到有效除Fe的作用； AZ80合金中分别添加1%(质量分数)的Ce和Y，可以显著细化合金的晶界第二相，并在晶界上分别生成针状的Al₁₁Ce₃相和块状的Al₂Y相；挤压变形后，Al-RE相在晶界上能够通过阻止位错运动而有效抑制再结晶晶粒长大；挤压+ T5处理后，含1%Y的合金具有最好的力学性能，抗拉强度和屈服强度分别达到390和250 MPa，而含1%Ce的合金无论是在挤压态还是T5处理后，其力学性能最低。

The effects of rare-earth Ce and Y on the melting, microstructure and mechanical properties of AZ80 Mg alloys were investigated by elementary analysis, mechanical properties examination, XRD, SEM and TEM. The experimental results show that the content of Fe decreases obviously during alloy melting, and the melting time is shortened when Y is added into AZ80. The as-cast microstructure of AZ80 alloys is refined, and needle-like Al₁₁Ce₃ and block-like Al₂(Y, Mn) phases generate at grain boundary when 1%Ce and 1%Y (mass fraction) are added into AZ80 alloys. After extrusion, the coarsening of recrystallized grain is depressed by Al-RE phases impeding motion of dislocation at grain boundary. And after extrusion+T5(177 ℃, 0-30 h) heat-treatment, the maximum tensile strength of AZ80 alloy containing 1%Y is obtained with ultimate tensile stress of 390 MPa and yield stress of 250 MPa.

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