Generalized stacking fault energy in magnesium alloys: Density functional theory calculations

Effects of Alloying Elements on Stacking Fault Energies and Electronic Structures of Binary Mg Alloys: A First-Principles Study

“…[39,51] The present setting is also in line with the experimentally determined concentrations of alloying element in the fault layers of Mg alloys, typically lower than 10 at% such as 2 ± 1 at%Zn-4 ± 2 at%Y, [52] 7 at%Zn-6 at%Y, [53] 6 at%Zn-9 at%Y, [54] and 3 at%Zn-6at%Y [53] in the alloys of Mg-1 at%Zn-2 at%Y. The different concentration of alloying elements is likely the reason for the discrepancy in reported data from Muzyk et al [23] and Zhang et al [22,24] Since the local chemical environments for alloying elements in I1 (ABC), I2 (ACB), and EF (ACB) are similar to that of FCC, the calculated stacking fault energies and the Mg-X supercell volumes are plotted in Figure 3 with respect to the volume of each individual alloying element X in the FCC structure. [31,38] It can be seen that the equilibrium volumes of Mg-X supercells increase almost linearly with the volume of alloying element X in the FCC structure.…”

“…It should be pointed out that the concentrations of alloying elements in a fault plane in the works by Muzyk et al [23] and Zhang et al [22,24] are 25 at% with all Mg atoms involved in Mg-X bonds and 11 at% with only one Mg-Mg bond, respectively, yielding strong interactions between alloying elements through X-Mg-X bonds in the fault plane. In the present work, the concentration of the alloying elements in the fault plane is 6.25 at% without the X-Mg-X bonds in the fault plane.…”

“…Theoretical investigations of stacking fault energies of some binary Mg-X alloys have recently been reported in the literature [22][23][24][25] along with contour plots of electron density in 2D and electron density isosurface figures in 3D, [26][27][28][29][30] however, the detailed chemical bond structures of the fault and non-fault layers and the contributions of alloying elements on the electronic structure of Mg with stacking faults have not been reported in the literature. In the present work, the effects of major alloying elements on the energies and bond structures of I1, I2, and EF of Mg-X alloys are systematically investigated through first-principles calculations in term of electron localization morphology.…”

“…Through the four parameters Birch-Murnaghan equation of state, [38] the total energies of I1, I2, and EF structures at equilibrium volume are obtained and [30] summarized in Table 1 along with various computational data in the literature with the majority of data for I1 from Zhang et al [22] and those of I2 from Zhang et al [24] and Muzyk et al [23] Correspondingly, the segregation behavior of the alloying element in stacking faults are obtained and shown in Figure 2. According to the crystal structures of each individual solute atom at room temperature, it can be seen that some alloying elements with HCP and FCC structures reduce the stacking fault energies the most.…”

Temperature-Dependent Generalized Planar Fault Energy and Twinnability of Mg Microalloyed with Er, Ho, Dy, Tb, and Gd: First-Principles Study

“…While sf can be measured experimentally, us and ut are difficult to be obtained from experimental measurements and can be determined only through atomic simulation, which represent the minimum energy barriers for partial dislocation nucleation [49] and microtwin nucleation, respectively. All the calculated fault energies ( sf , us , and ut ) at different temperature for pure Mg and Mg-based alloys are summarized in Table 2 [18,21,51]. Therefore, the calculation of this work should be reasonable and reliable.…”