Precipitate evolution of as-cast Mg-9Gd-2Y-0.5Zn-0.5Zr alloy containing LPSO, ???, ?? and ?'' phases during isothermal aging at 200?C

In this work, the evolution process, crystallinity, microstructure and morphology of Mg-9Gd-2Y-0.5Zn-0.5Zr (wt %) alloy precipitates were analyzed during isothermal aging at 200 degrees C. During the early stages of aging, the precipitate phase distributed in the matrix is mainly the beta '' phase, which exhibits a hexagonal D019 structure. In the peak-aged stage, the gamma '' phase, LPSO phase, and beta ' of the precipitates coexist in the matrix. The synergism between the three types of phases is significant with respect to the improved age-hardening. We propose that the optimized mechanical properties of the alloy originate from the co-precipitation of the LPSO, beta ', and gamma center dot center dot phases. Furthermore, it is an important way to improve the performance of the alloy at high temperatures.(c) 2022 Published by Elsevier B.V.