First-principles calculations to investigate structural stability, electronic properties and mechanical properties of Y element substitutional doped β′-Mg7Gd phase

Abstract

Based on the experimental characterization results of aberration-corrected (Cs) high-angle-annular dark field-scanning transmission electron microscopy (HAADF-STEM) and energy dispersive X-ray spectrometry (EDS) diagrams, we systematically investigated the performance of substituting Y for Gd in the β′-Mg7Gd phase. The formation enthalpy, electronic structure, and elastic properties were calculated by first-principles. The calculation results indicated that all structures are thermodynamically stable, and the substitutional doping of one Gd atom replaced by one Y atom is the most stable. The electronic structure plots for the energy of the whole system decreased near the Fermi level, indicating that the system became more stable after substitutional doping. Furthermore, the elastic modulus, particularly Young's modulus and shear modulus, was greatly improved in Mg28Y2Gd2(P2). Elastic anisotropy factors are calculated to evaluate elastic anisotropy, and plot the three-dimensional and projection plots of bulk, shear, and Young's modulus. The extent of elastic anisotropy is ranked as follows: Mg28Y2Gd2(P2) > Mg7Gd(P0) > Mg28YGd3(P1). These results offer valuable data references for the performance evaluation and practical application of rare earth (RE) magnesium alloys.