稀土Ce和Y對AZ80鎂合金組織和力學性能的影響Effects of rare-earth Ce and Y on microstructure and mechanical properties of AZ80 Mg alloys

通過元素分析、性能測試、XRD、SEM和TEM等手段分析了稀土Ce和Y對AZ80鎂合金熔煉、組織和力學性能的影響規律。結果表明：在AZ80合金熔煉過程中，添加稀土Y元素能夠起到有效除Fe的作用； AZ80合金中分別添加1%(質量分數)的Ce和Y，可以顯著細化合金的晶界第二相，并在晶界上分別生成針狀的Al₁₁Ce₃相和塊狀的Al₂Y相；擠壓變形后，Al-RE相在晶界上能夠通過阻止位錯運動而有效抑制再結晶晶粒長大；擠壓+ T5處理后，含1%Y的合金具有最好的力學性能，抗拉強度和屈服強度分別達到390和250 MPa，而含1%Ce的合金無論是在擠壓態還是T5處理后，其力學性能最低。

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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