The influence of RE elements on the performance of laser welded joints of magnesium alloys: A review

Among existing lightweight metals, magnesium (Mg) alloys have garnered significant attention due to their exceptional specific strength. However, their laser welding applications face challenges from porosity, cracking, and grain coarsening defects. Rare earth (RE) elements, leveraging their unique strengthening effects, offer a promising solution for refining weld microstructures and suppressing welding defects. Nevertheless, a systematic review of RE-enhanced mechanisms and defect suppression strategies remains lacking. This paper systematically reviews recent research advancements in Mg alloy laser welding, with a focused elucidation of the governing effects of welding parameters on weld performance, and the core mechanistic roles of RE elements in the welded joint. Furthermore, we discuss key challenges and future directions in process optimization, service performance enhancement, and industrial scalability of RE-modified Mg alloy welding. The findings aim to provide theoretical foundations for designing high-performance welded Mg-RE structures and advance lightweight manufacturing technologies in aerospace, electric vehicles, and other cutting-edge industries.