Dissolution behavior of dizinc magnesium phase in Al-Zn-Mg-Cu alloy

The presence of the dizinc magnesium (MgZn2) phase in Al-Zn-Mg-Cu alloy significantly enhances its mechanical properties due to the high density, uniform distribution, and fine size of the MgZn2 phase. While previous studies have focused on precipitation evolution during solid solution and aging, little attention has been given to dissolution behavior. The dissolution behavior of MgZn2 phase during heat treatment was studied by changing the heat treatment temperature and time in the article. It was found to be completely dissolved at 480 degrees C and 490 degrees C/60 min. Experimental results were fitted to establish the relationship between the volume fraction of the MgZn2 phase and time at temperatures ranging from 460 to 490 degrees C. Additionally, a kinetic model for dissolution process was derived based on classical particle system dissolution model and diffusion-controlled transformation theory with adjusted parameters representing physical quantities accurately. These results are helpful to obtain precipitates with smaller size, more quantity and better dispersion, which is of great significance for improving the mechanical properties of the alloy.Graphical abstractKinetic model of solute diffusion including MgZn2/Al-matrix interface is established based on the classical dissolution model.