Formation of β′ phase in LPSO structures in an Mg88Co5Y7 alloy

Formation of beta' phase in long-period stacking ordered (LPSO) structures in an Mg88Co5Y7 (at.%) alloy after aging at 200 degrees C for 24 h or electron beam (EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). beta' phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 degrees C for 24 h. LPSO structure containing stacking defects transforms into the beta'-long phase during EB irradiation, which plays a key role in accelerating solute atoms' diffusion. New complex beta' (LPSO) structures formed in the alloy after EB irradiation, such as beta' (12H) structure with an orthorhombic lattice (Mg7Y, Cmcm, a = 2a(0) = 0.642 nm, b = 4 root 3a(0) = 2.27 nm, c = 6c(0) = 3.12 nm). (c) 2020 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer review under responsibility of Chongqing University

Automated summary

The formation of beta' phase in an Mg88Co5Y7 alloy after aging or electron beam irradiation has been studied using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). It was found that beta' phase precipitated only in the Mg matrix and not in the LPSO structures after aging. However, the LPSO structures with stacking defects transformed into the beta'-long phase during electron beam irradiation.