Nanocrystallization and precipitation behavior evolution of AZ80 magnesium alloy during multi-directional compression

Abstract

In response to the growing demand for high-performance magnesium alloys in the aerospace and transportation industries, researchers conducted a study on the AZ80 magnesium alloy. The primary objective was to achieve a nanocrystalline structure in the alloy through severe plastic deformation using low-strain multi-directional compression at room temperature. Subsequently, an aging treatment was performed to induce the transformation of the structure into a stable state. The study aimed to investigate the morphology and mode of the second phase precipitation in the magnesium alloy after undergoing severe plastic deformation. The research findings revealed that the application of multi-directional and multi-pass compression during room temperature deformation of the magnesium alloy effectively prevented instability and fracture. Moreover, this process facilitated the accumulation of larger true strain. As the number of compression passes increased, deformation twins became increasingly denser, particularly in the intersecting areas. Consequently, ultrafine high-angle grain structures were preferentially formed in these regions. Furthermore, the number of fine-grained areas gradually increased with each deformation pass. After ΣΔε 5.12, the grain size was refined to a range of 100–200 nm. Additionally, the aging treatment following severe plastic deformation brought about a significant change in the traditional lamellar precipitation mode of the second phase Mg₁₇Al₁₂ in the magnesium alloy. Instead, spherical precipitation occurred.