Grain Refinement Mechanism and Research Progress of Magnesium Alloy Incorporating Zr

Grain refinement stands out as the primary strengthening mechanism in magnesium alloys. Zr emerges as the most effective grain refiner for magnesium alloys in the absence of Al, Si, etc. Typically, Zr is introduced in the form of an Mg-Zr master alloy. The crucial factor for achieving effective grain refinement in magnesium alloys incorporating Zr lies in regulating the morphology of Zr elements in the Mg-Zr master alloy, distinguishing between particle Zr and solute Zr. This study presents the theoretical groundwork for grain refinement. Drawing upon the growth restriction theory and heterogeneous nucleation theory, the refinement mechanism of soluble Zr and particle Zr on magnesium alloys is discussed. The discussion also identifies the engineering application bottleneck associated with Zr-refined magnesium alloys. A comprehensive review of advancements in Zr-refined magnesium alloy research is conducted, encompassing particle Zr and solute Zr. This review highlights the synergistic design strategy proposed for Zr-refined magnesium alloys. Ultimately, the anticipated development trends for Zr-refined magnesium alloys is prospected.