Effects of icosahedral phase on mechanical anisotropy of as-extruded Mg-14Li (in wt%) based alloys

Abstract

Through investigating and comparing microstructure and crystallographic texture of as-extruded Mg-14Li and Mg-14Li-6Zn-1Y (in wt%) alloys, the differences in their mechanical anisotropy were investigated. It revealed that the formation of I-phase (Mg3Zn6Y, icosahedral structure) can effectively refine grain size. Moreover, compared with Mg-14Li alloy, the texture type of Mg-14Li-6Zn-1Y alloy changed slightly, but its texture intensity decreased remarkably. As a result, the stronger texture contributed to the “normal” mechanical anisotropy of Mg-14Li alloy with higher tensile strength and a lower elongation ratio along transverse direction (TD) than those along extrusion direction (ED). However, for Mg-14Li-6Zn-1Y alloy, the zonal distribution of I-phase particles along ED caused “abnormal” mechanical anisotropy, i.e. higher tensile strength and better plasticity along ED.