Mechanical Behavior and Physical Properties of Mg Binary Alloys via Y-doping: Molecular Dynamic Study

The effects of doping concentration and doping models of yttrium (Y) on mechanical behaviors are researched by using molecular dynamics and the second nearest-neighbor modified embedded-atom method (2NN-MEAM) formalism for nano Mg-Y alloy systems. The results confirm the effect of Y-doping on the mechanical properties and the polycrystalline structure of Mg-Y alloys. When the content of Y atoms is about 7-8%, the models of pristine doping and grain boundaries (GBs) doping have the highest Young's modulus, and the strength also increases obviously. Doping Y atoms at GBs can enhance the stability of GBs and significantly improve the elastic modulus and strength of nano Mg alloys. And the smaller the grain size is, the more obvious the strengthening effect is. As the grain size decreases to the critical value, Young's modulus of the nano Mg-Y alloys decreases, and the strengthening effect weakens. These results have important guiding significance for the design and improvement of mechanical properties of Mg-Y alloys and will provide references for preparing high strength nano Mg alloys materials by controlling impurity atoms doping.