Microstructure and mechanical behavior of AXM Mg alloy systems—A review

•Role of Ca/Al ratio in AXM Mg alloy systems for the mechanical behavior.•Influence of amount of alloying elements like Al, Ca, and Mn on the formation of precipitation in AXM Mg alloy systems.•Significance of precipitate formation in monoatomic layer G.P zones for enhancing both strength and ductility.•Importance of co-segregation behavior to enhance the stretch formability of the AXM Mg alloy systems. Automobiles are the inevitable mode of transportation. However, increasing fuel prices and carbon dioxide emissions are posing a serious threat to automobile users and the environment. Thus, the development of new lightweight materials has been a key area of research. Magnesium-based commercial alloys (AZ and ZK series alloys) are the lightest among all structural metals. However, there is still a question about the replacement of Aluminum-based alloys due to HCP crystal structure. In this connection, MgAlCaMn (AXM) Mg alloy can be a choice as an alternative to the existing Mg-based commercial alloys for structural applications. It contains (Al, Mg)2Ca, Al2Ca, Mg2Ca, and Al8Mn5 as the secondary phases, contributing to the microstructural refinement and property enhancement. However, the formation of those precipitates depends on the amount of Al, Ca, and Mn, especially, the Ca/Al ratio. In addition, the secondary processes influence the grain refinement and property enhancement of texture modifications. Hence, this review article focuses on elaborating on the significance of the Ca/Al ratio for the precipitate formation, secondary process, and texture modifications. The co-segregation behavior of other micro-alloying elements like Cerium, Lanthanum, and Zinc in AXM Mg alloy systems has also been discussed for property enhancement. [Display omitted]