Influences of alloying composition and cooling rate on precipitation behaviors of primary Al3Zr-D023 intermetallics in Al-Mg-Li-Zr alloys

Abstract

In the industrial process, the potential benefit of Al3Zr precipitates is usually weakened because coarse Al3Zr precipitates have no positive effect on the dynamic recovery, recrystallization and grain growth. Effects of alloying composition and cooling rate on precipitation and growth behaviors of primary Al3Zr-D023 intermetallics were investigated, especially in a large compositional space. Four types of elements exist in the Al3Zr-D023 phase. Increasing initial Mg, Li, Zr, and Ti contents is beneficial to increase the start precipitation temperature of Al3Zr-D023 particles. Increasing initial Mg, Li, Zr, Ti contents and reducing cooling rate are beneficial to increase the mean length, decrease the nucleation rate and the number density of Al3Zr-D023 precipitates. Furthermore, Zr and Ti element contents show a strong positive correlation with the start precipitation temperature and the final length of Al3Zr-D023 precipitates. Reducing slightly initial Ti content is beneficial to reduce the final length of Al3Zr-D023 precipitates. Furthermore, two empirical equations were obtained using the multiple linear regression method, which reveal the complex interactions rather than single-element effect of Mg, Li, Zr, and Ti.