The role of melt cooling rate on the interface between 18R and Mg matrix in Mg 97 Zn 1 Y 2 alloys

The role of melt cooling rate on the interface morphology and dislocation configuration between 18R long-period stacking ordered (LPSO) structure and Mg matrix in Mg 97 Zn 1 Y 2 (at.%) alloys was investigated by atomic-scale HAADF-STEM imaging. The 18R/Mg interface is step-like both in the near-equilibrium alloy and non-equilibrium alloy. Lower cooling rate makes the step size more regular and larger. Only 54R structure can be observed at the interface in the near-equilibrium alloy, and the dislocations are highly ordered. 54R and 54R ' structure sandwiched by b 1 and b 2 + b 3 dislocation arrays, and new dislocation configuration can be detected at the interface in the non-equilibrium alloy, but the dislocations are less ordered. 18R/Mg interface containing 54R or 54R ' in equilibrium width, parallel to the (01 1 over bar 0) plane, should be most stable based on elastic calculation. The segregation of solute atoms and its strong interaction with dislocations dominate the LPSO/Mg interface via diffusion-displacive transformation. (c) 2021 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