Investigation of the separation behavior in recycling Nd-containing magnesium alloy waste using a vacuum method

Magnesium alloys, regarded as the most promising structural materials for lightweight applications, have gained enhanced strength and heat resistance through the addition of rare earth elements, leading to their widespread use in aerospace and defense industries. However, with the growing volume of end-of-life components and inherently low production yields, the efficient recycling of rare earth-containing magnesium alloys has become increasingly critical. This study explores the separation and enrichment behavior of magnesium and neodymium during the vacuum recycling of rare earth magnesium alloys, utilizing gas-liquid phase theory and phase diagram computational methods. Both theoretical analyses and experimental results indicate that the separation process in the Mg-Nd system—whether by vacuum distillation or gasification—follows a consistent phase transformation sequence: Mg₄₁Nd₅ → Mg₃Nd → MgNd → Nd. Two distinct neodymium-rich morphologies were observed: a loose porous structure and a dense, compact form. Notably, vacuum gasification of ZM6 rare earth magnesium alloy resulted in a neodymium concentration of 82.91 wt.% in the solid residue. The process demonstrated high direct recovery efficiency, rapid separation kinetics, and zero secondary waste generation—establishing it as a green and highly efficient recycling approach for magnesium alloy scrap. These findings provide fundamental theoretical and practical support for the recycling of Nd-containing magnesium alloys and contribute to the sustainable utilization of secondary rare earth resources.