Abstract: After solution treatment at 477 ℃ for 1 h, the Al-6.15Zn-1.41Mg-1.45Cu alloy was treated by two-stage aging based on pulsed magnetic field. The effect of pulsed magnetic field on the precipitated phase and mechanical properties of the Al-6.15Zn-1.41Mg-1.45Cu alloy during aging was studied by changing the aging time and comparing with the conventional two-stage aging structure and properties. The diffusion mechanism of precipitated phase accelerated precipitation in the Al-6.15Zn-1.41Mg-1.45Cu alloy during two-stage aging in pulsed magnetic field was analyzed with kinetics. The precipitation phase and tensile fracture morphology of the Al-6.15Zn-1.41Mg-1.45Cu alloy were observed by SEM, and the mechanical properties were tested. The results show that the pulsed magnetic field increases the diffusion coefficient and nucleation rate of the precipitated phase during aging process of the Al-6.15Zn-1.41Mg-1.45Cu alloy, resulting in the appearance of diffusely fine precipitated phases in the matrix after aging. After two-stage aging pulsed magnetic field (121 ℃×90 min+177 ℃×60 min), the tensile strength is 495.43 MPa, and hardness is 156.3 HV5. Compared with the conventional two-stage aging treatment, the tensile strength increases by 20.83%, hardness increases by 17.89% and the aging holding time reduces by 87.5%.

Key words: pulse magnetic field, two-stage aging, mechanical properties, spread