Effect of the morphology of long-period stacking ordered phase on mechanical properties and corrosion behavior of cast Mg-Zn-Y-Ti alloy

In this study, three different morphologies of long-period stacking ordered (LPSO) phase, i.e. lamellar, block-like, and rod-like, were obtained through various heat treatment processes. The effect of the morphology of LPSO phase on mechanical properties and corrosion behavior of cast Mg-Zn-Y-Ti alloy was investigated accordingly. The results suggested that the block-like LPSO phases in the as-cast alloy transformed into the rod-like LPSO phases during heat treatment at high temperature, while the low temperature was conducive to the precipitation of lamellar phases in the grain interior. The formation of the rod-like LPSO phases resulted in an increase of 42% in elongation while maintaining a high tensile strength. In addition, the alloys with the rod-like LPSO phases exhibited more uniform corrosion mode and better corrosion resistance than the alloys with the block-like LPSO phases, so the former had excellent comprehensive properties. The precipitation of the lamellar LPSO phases not only reduced the mechanical properties, but also accelerated the corrosion rate and produced severe localized corrosion. Therefore, the mechanical properties and corrosion resistance of the alloys could be improved by regulating the morphology of LPSO phases.