【摘要】 以4种不同Sc/Zr比的Al-5.0Mg-3.0Zn合金为研究对象,研究了不同Sc/Zr比对时效态合金微观组织及力学性能的影响。利用透射电子显微镜（TEM）、电子背散射衍射（EBSD）、X射线衍射（XRD）、扫描电子显微镜（SEM）和室温拉伸实验方法,探究了Sc、Zr微合金化对合金析出强化相T-Mg₃₂（Al,Zn）₄₉的影响,并对不同强化机制对屈服强度的贡献进行了定量计算。结果表明:合金中析出了大量弥散分布的T相,不同Sc/Zr比对T相析出未产生显著影响,4种合金中T相尺寸、数量密度和体积分数差异不大,且该相均与Al基体完全共格;与基础合金相比,复合添加Sc、Zr合金中的晶粒明显细化,位错密度更高。合金中主要的强化机制为T相的析出强化,其对屈服强度的贡献为282.5～296.9 MPa;固溶强化对合金屈服强度的贡献为33.3～40 MPa;复合添加Sc、Zr通过细晶强化提高了合金的屈服强度约47.8～63.6 MPa;复合添加Sc、Zr并未改变合金的拉伸断裂方式。4种强化机制共同作用下Sc/Zr比为0.9和1.2合金的抗拉强度为551～552 MPa,屈服强度为461～463 MPa,延伸率为17.7%～18.0%。更多还原

【Abstract】 Four Al-Mg-Zn alloys with different Sc/Zr ratios were studied,and the influence of Sc/Zr ratio on the microstructure and mechanical properties of Al-Mg-Zn alloys in aged state was studied.Transmission electron microscopy（TEM）,electron backscatter diffraction（EBSD）,X-ray diffraction（XRD）,scanning electron microscopy（SEM） and room temperature tensile experiment were used to investigate the effect of Sc and Zr microalloying on the precipitation of T-Mg₃₂（Al,Zn）₄₉ phase,and the contribution of different strengthening mechanisms to yield strength was quantitatively calculated.The results show that a large amount of T phase is dispersed in Al-Mg-Zn alloy with small size,and different Sc/Zr ratio has no significant effect on T phase.There is no significant difference is size,number density and volume fraction of T phase in the four alloys,and the T phase is completely coherent with Al matrix.Compared with the case in the base alloy,the grains in the composite alloy with Sc and Zr additions are significantly refined,and the dislocation density is higher.The main strengthening mechanism of Al-Mg-Zn alloy is the precipitation strengthening of T phase,which contributes 282.5-296.9 MPa to the strength.The contribution of solid solution strengthening to the yield strength of the alloy is 33.3-40 MPa.The mechanical properties of the alloy are improved by the addition of Sc and Zr,and the yield strength of the alloy is increased by 47.8-63.6 MPa through fine grain strengthening.The addition of Sc and Zr does not change the tensile fracture mode of the alloy.The tensile strength of 0.13Sc-0.15Zr alloys and 0.17Sc-0.14Zr alloys is 551-552 MPa,the yield strength is 461-463 MPa and the elongation is 17.7%-18.0%.更多还原