The Effects of Alloying Elements on the Microstructure of Al-Zn alloy

Abstract

—The effects of alloying elements and rare earth elements such as Zr, Sc, Er, etc., are presented. Structural analysis shows that these rare earth elements all form an intermetallic phase with Al, with the same formula Al3RE. This intermetallic phase plays a role in preventing the formation of harmful phases in the alloy. These intermetallic phases can be located within the grain, acting as heterogeneous nucleation centers or at the grain boundary, blocking positions to prevent grain growth. The research presented the roles of the intermetallic phase as the crystallization seed center and the intermetallic phase as the inhibitory phase for grain growth. XRD analysis results have determined the structure of these intermetallic phases, showing their conformity with the background phase. Through theoretical and experimental studies, the deformation and uniform annealing process for the Al-Zn-Mg-Cu alloy was determined in the presence of La and Ce grain refiners. The uniform annealing process removed the dendritic structures after casting and determined the intermetallic phases’ role in preventing the matrix phase’s growth. XRD analysis results confirmed the structure of the intermetallic phases, demonstrating their conformity with the matrix phase. Research about the influence of rare earth elements in the grain reduction process will help establish a grain reduction protocol for studying alloys during both the melting and homogenization annealing stages. This is particularly crucial for creating high mechanical strength and superplastic alloys within this alloy group.