Effect of non-isothermal aging on microstructure and properties of Al-5.87Zn-2.07Mg-2.42Cu alloys

The evolution of microstructure and properties of Al-5.87Zn-2.07Mg-2.42Cu alloys during non-isothermal aging was studied. The mechanical properties of the alloy were tested by stretching at room temperature. The results show that in the non-isothermal aging process, when the alloy is cooled to 140 degrees C, the ultimate tensile strength of the alloy reaches a maximum value of 582 MPa and the elongation is 11.9%. The microstructure was tested through a transmission electron microscope, and the experimental results show that the GP zones and eta' phases are the main strengthening precipitates. At the cooling stage, when the temperature dropped to 180 degrees C, the GP zones were precipitated again. Besides, the experimental results show that the main strengthening phase during non-isothermal aging is eta' phases.