An atomistic study of dislocation-solute interaction in Mg-Al alloys

In this study, atomistic simulations are performed to study the dislocation-Al solute effect on the strength of Mg alloys. At temperature T = 0 K, molecular mechanics simulations are carried out to investigate the effect of Al solute concentration on the Peierls stress of basal plane edge and screw dislocations. It is found that the Peierls stress will increase by at least one order of magnitude when 0.25 at% Al atoms are randomly introduced in the Mg alloys with an edge dislocation. Generally, the Peierls stress will increase with the increase of the Al concentration up to 8 at%. Furthermore, the interaction between the basal plane edge dislocation and Al solute at T = 300 K is studied using molecular dynamics. It appears from the simulations that the critical shear stress increases with the Al solute concentration. Comparing with the solute effect at T = 0 K, however, the critical shear stress at T = 300 K is lower since the kinetic energy of the atoms can help the dislocation conquer the energy barriers created by the Al atoms.