时效处理对7022铝合金组织与性能的影响

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

采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、电子背散射衍射(EBSD)和万能材料试验机等研究了时效处理对7022铝合金组织及性能的影响。结果表明:固溶处理后的7022铝合金的组织主要由α-Al、MgZn_(2)、Al_(2)CuMg和Al_(7)Cu_(2)Fe相组成。随着时效的进行,Al_(2)CuMg和Al_(7)Cu_(2)Fe相逐渐溶解,并且Cu原子替代Zn原子形成与MgZn_(2)性质类似的Mg(Zn,Cu,Al)_(2)相,并产生显著的时效析出硬化效应。同时晶粒出现明显长大,在70℃下时效10 h、110℃下时效10和14 h和150℃下时效10 h后晶粒尺寸的增长率分别为10.8%、16.2%、27.0%和35.1%。试样的抗拉强度、屈服强度和伸长率受析出强化和细晶强化的共同影响,最大值分别为617.3 MPa、568.6 MPa和25.8%。试样的断裂行为主要受到晶粒尺寸和第二相数目、尺寸的影响。

Effect of aging treatment on microstructure and properties of 7022 aluminum alloy were studied by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)analysis,X-ray diffraction(XRD),electron backscatter diffraction(EBSD)technique and universal material testing machine.The results show that the microstructure of the 7022 aluminum alloy after solution treatment is mainly composed ofα-Al,MgZn_(2),Al_(2)CuMg and Al_(7)Cu_(2)Fe phases.During aging,the Al_(2)CuMg and Al_(7)Cu_(2)Fe phases gradually dissolve,and Cu atoms replace Zn atoms to form Mg(Zn,Cu,Al)_(2)phase with similar properties to MgZn_(2),resulting in significant aging precipitation hardening effect.The grain size of the alloy increases significantly after aging treatment,compared with the original grain size of the alloy,the grain size of the alloy increases by 10.8%,16.2%,27.0%and 35.1%after aging at 70℃for 10 h,110℃for 10 and 14 h and 150℃for 10 h,respectively.The tensile strength,yield strength and elongation of the alloy are affected by precipitation strengthening and fine grain strengthening,and the maximum values are 617.3 MPa,568.6 MPa and 25.8%,respectively.The fracture behavior of the alloy is mainly affected by the grain size,the number and size of the second phase.