时效处理对7022铝合金组织与弯曲性能的影响

采用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)、电子背散射衍射(EBSD)、拉伸和弯曲试验等研究了时效处理对7022铝合金组织及弯曲性能的影响。结果表明,固溶处理后7022铝合金基体中依然含有大量黑色不溶第二相,且这些相主要由α-Al、MgZn₂、Al₂CuMg和Al₇Cu₂Fe相组成。随着时效的进行,Al₂CuMg和Al₇Cu₂Fe相逐渐溶解,与MgZn₂相性质相似的Mg(Zn, Cu, Al)₂相析出,同时晶粒逐渐长大,产生明显的析出强化效应。试样的抗弯强度主要受到第二相颗粒的数目、尺寸以及晶粒尺寸的影响。110 ℃×10 h时效条件下,合金拥有弥散分布的细小第二相颗粒和合适的晶粒尺寸,具有较好的抗弯强度和抗拉强度,其数值分别为21.7 MPa、608 MPa。

Effect of aging on microstructure and bending properties of 7022 aluminum alloy

Effect of aging treatment on microstructure and mechanical properties of 7022 aluminum alloy was studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) analysis, X-ray diffraction (XRD), electron backscatter diffraction (EBSD), tensile and bending test. The results show that the 7022 aluminum alloy matrix after solution treatment still contains a large amount of black insoluble second phases and these phases are mainly composed of α-Al, MgZn₂, Al₂CuMg and Al₇Cu₂Fe phases. As the aging progresses, the Al₂CuMg and Al₇Cu₂Fe phases gradually dissolve, and the Mg(Zn, Cu, Al)₂ phase, which is similar in properties to the MgZn₂ phase, precipitates, and the grains grow gradually, resulting in an obvious precipitation strengthening effect. The bending strength of the specimen is mainly affected by the number and size of the second phase particles and grain size. Under the aging condition at 110 ℃ for 10 h, the alloy with dispersed fine second phase particles and suitable grain size has better bending strength and tensile strength, and the values are 21.7 MPa and 608 MPa, respectively.