First principles investigation of β′-short and β′-long in Mg–Gd alloy

We use density functional theory calculations to explain why β′-long instead of β′-short forms during age-hardening process in Mg–Gd alloys. We calculate strain energies and interfacial energies of β″, β′-short and β′-long in Mg–Gd alloys and find that (1) results of strain energies and interfacial energies of β″ agree well with other theoretical works (2) habit plane of β′-long predicted by density functional theory calculations is consistent with experimental observation (3) strain energy is mainly responsible for the formation of β′-long instead of β′-short in the age-hardening process. •We calculated the strain energy and interfacial energy of β″ precipitate.•We compared strain energy and interfacial energy of β′-short and β′-long.•We find strain energy is the reason why only β′-long forms.