LAUSR

Abstract First-principles calculation of the theoretical critical shear strength ( τ m a x ) (reflecting the value of critical resolved shear stress) was performed on pure Mg and Mg-Sn models for basal and pyramidal slip systems. The effects of Sn content on the formability of Mg-Sn monophasic solid solution (MSS) alloys and the mechanical behavior of the as-extruded Mg-Sn sheets were also investigated. The calculated results showed that after doping Sn atoms to pure Mg, the τ m a x in basal slip increased from 114 to 149 MPa, while that in pyramidal slip decreased from 1571 to 446 MPa. The decreased τ m a x ratio of the pyramidal slip to the basal slip might make the pyramidal slip systems more likely to be activated, leading to an improvement in the formability of Mg-Sn alloys. This result was further confirmed by experimental observations: with increasing Sn content, the formability of Mg-Sn MSS alloys and the ductility of as-extruded Mg-Sn sheets were all enhanced, accompanied by weakened basal texture.