The effect of Mg17Al12 intermetallic compound on dynamic recrystallization of cast-forged AZ80 magnesium alloy

An asymmetric I-crossbeam geometry is produced by cast-forging of the AZ80 magnesium alloy at two different casting cooling conditions and three different forging temperatures. Samples are extracted from two different locations from each component, representing different deformation conditions, for microstructure study. This paper presents a detailed investigation into the relationship between the Mg17Al12 intermetallic compound and dynamic recrystallization in the cast-forging process. The eutectic, lamellar, discontinuous, and continuous morphologies of the Mg17Al12 phase are observed in the produced components, and their evolution during the cast-forging process is investigated. Depending on the forging condition, dissolution and re-precipitation of the Mg17Al12 phase might occur before or after the forging stage and influence the extent, distribution, and grain size of DRX. It is shown that the eutectic, lamellar, and discontinuous morphologies of the Mg17Al12 phase effectively promote dynamic recrystallization. On the other hand, the continuous morphology is only effective when the particles are broken as a result of high deformation. This study provides a better understanding of the effect of Mg17Al12 intermetallic compound on the hot deformation behavior of the AZ80 alloy, which can be used to tailor the cast material in order to improve the forgeability and final mechanical properties of the magnesium-based structural components. [Display omitted] •Casting cooling rates lead to different dynamic recrystallization behavior.•Continuous Mg17Al12 promotes DRX when particles are broken down due to deformation.•EBSD reveals Mg17Al12 distribution impact on distribution and size of DRXed grains.•Depending on thermomechanical process, precipitation occurs before or after forging.