Electronic structures of long periodic stacking order structures in Mg: A first-principles study

Long period stacking order (LPSO) structures, such as 6H, 10H, 14H, 18R and 24R, play significant roles in enhancing the mechanical properties of Mg alloys and have been largely investigated separately. In the present work, through detailed investigations of deformation electron density, we show that the electron structures of 10H, 14H, 18R and 24R LPSO structures in Mg originate from those of deformation stacking faults in Mg, and their formation energies can be scaled with respect to formation energy and the number of layers of deformation stacking faults, while the electron structure and formation energy of the 6H LPSO structure are between those of deformation and growth stacking faults. The simulated images of high resolution transmission electron microscopy compare well with experimental observed ones. The understanding of LPSO structures in Mg enables future quantitative investigations of effects of alloying elements on properties of LPSO structures and Mg alloys.