Experiment and first-principles calculation to investigate the phenomenon of Gd and Y elemental enrichments in the long-period stacking ordered phase

Abstract

In this study, the Gd and Y elemental enrichment in long-period stacking ordered (LPSO) phases has been systematically studied by combining energy dispersive X-ray spectrometry (EDS) diagram and first-principles calculation. This phenomenon differs from the ordinary type of LPSO phase, which consists of only one rare earth element. It is highly likely that the observed effect is attributed to the preferential formation of the Mg-Y-Zn LPSO phase, which is subsequently replaced by the Gd element to form more stable Mg-Gd-Y-Zn LPSO phases. The results of the formation enthalpy and energy suggest that the most probable situation is one group of Gd (four atoms) replacing the Y atoms. The electronic properties and elastic properties were performed to investigate the bonding character and mechanical stability. It can be found that the substitutional doping of the Gd element is able to improve bonding strength and increase anisotropy. Therefore, this research explains the interesting phenomenon of Gd and Y elemental enrichment for in-depth understanding of LPSO phases, and provides valuable data that can be utilized for designing rare-earth magnesium alloys with improved properties.