Microstructure and Mechanical Properties of the AlCrFeCoNi_p/AZ91D Composites After Heat Treatment

To enhance the comprehensive performance of Mg matrix composites, as-cast AlCrFeCoNi_p/AZ91D composites with different reinforcement contents were heat treated. Optical microscopy, scanning electron microscopy, and transmission electron microscopy were employed to characterize the microstructure evolution. The experimental results reveal that with the increasing content of AlCoNiCrFe particles, the average grain size of matrix and quantity of the β-Mg₁₇Al₁₂ phases decreased, and the morphology of β-Mg₁₇Al₁₂ phase changed. There was no intermetallic compound formed at the AlCrFeCoNi/α-Mg interface, and the AlCrFeCoNi particles’ partial dissolution occured. After solution treatment at 673 K for 24 h and aging at 443 K for 16 h, the nominal component 10 vol.% composite obtained the best strength performance. The results demonstrated that variations in the quantity and shape of the β-Mg₁₇Al₁₂ phases, grain refinement strengthening, and CTE mismatch strengthening were mainly responsible for changes in the strength properties of the composites.