An in-situ study on the dissolution of intermetallic compounds in the Al-Zn-Mg-Cu alloy

The in-situ SEM observations and Line-scanning methods were used to observe the atomic concentration distribution and evolution of main elements in intermetallic phase at different solid solution temperatures. The results indicated that the atomic distribution of main elements in eta (MgZn2), S (Al2CuMg), Fe-containing (Al7Cu2Fe) intermetallic phases are parabolic through these phases, while the non-main elements uniformly distribute in matrix. The results of Differential Scanning Calorimetry (DSC) and Energy Dispersive Spectra (EDS) indicated that the Zn atoms dissolved into the matrix between 245 and 430 degrees C, under which the process of B phase transits to S phase occurred. The Cu element of S (Al2CuMg) phase has an obviously diffusion rate at 450 degrees C, while the Mg element has an obviously diffusion rate when the temperature is higher than 460 degrees C. Afterwards the atomic concentration dissolution was modelled by diffusion law, and the model results is corresponding to the linear rule, which agrees with the experiment results. (C) 2020 Elsevier B.V. All rights reserved.