Mg-Sn alloy is a high temperature-creep resistant magnesium alloy that has potential ap-plications in lightweight automobiles.The addition of Sn to Mg can reduce the overall cost of the alloy as Sn is cheaper than rare earth elements.Sn and Mg form Mg2Sn phase on the grain boundary,and this Mg2Sn phase has an excellent precipitation hardening effect.However,coarsened Mg2Sn phase can re-duce the age hardening effect of the alloy.Previous experimental studies have showed that the addition of Al element can considerably improve the age hardening effect of Mg-Sn alloy as it segregated at the in-terface between the Mg matrix and Mg2Sn phase.However,there is a lack of research on the different ori-entations of Al-doped Mg matrix and Mg2Sn phase and the distribution position of Al element at the inter-face.Therefore,in this study,the interface adhesion energy,interface energy,and interface doping en-ergy of Al-doped Mg/Mg2Sn with different index surfaces were calculated based on density functional theory to determine more stable doping positions.The effects of Al doping on the electronic structure of Mg(0001)/Mg2Sn(022)interface were analyzed using the density of states and crystal orbital Hamilton population.The results demonstrate that only a part of the Al-doping positions is beneficial in strengthen-ing the stability of Mg/Mg2Sn interface.After the addition of Al,the adhesion energy of Sn termination at Mg(0001)/Mg2Sn(001)interface is higher than that of Mg termination,but the adhesion energy of Sn ter-mination at Mg(0001)/Mg2Sn(111)interface is lower than that of Mg termination.In addition,the interface energy of Mg(0001)/Mg2Sn(022)interface doped with Al decreased by 0.07 eV/nm compared to that of Mg(0001)/Mg2Sn(022)interface.The addition of Al element to Mg(0001)/Mg2Sn(022)facilitates the doping of a special position,which shows an obvious interaction between the s orbital of Al and the p orbital of Sn after Al doping.Moreover,the Al—Sn bonding is found to be dominant at the interface.
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