Unveiling the strengthening effect of LPSO phase in a Mg-Y-Zn alloy

• Four different LPSO distributions were prepared in the same composition of Mg alloy. • The contribution of LPSO phase to yield strength was quantitatively investigated. • Type I LPSO was better for strengthening Mg alloys than Type II phase. • The formation of LPSO phase strongly compromises solid-solution strengthening. The volume fraction and distribution of long-period stacking ordered (LPSO) phase have a great influence on strengthening Mg alloys. In this work, four model Mg-8.81Y-0.88Zn (wt. %) alloys were designed to quantitatively investigate the contribution of LPSO phase to yield strength in tension. The LPSO phase formed at grain boundary (Type I) has a higher strengthening effect than that formed within the α-Mg matrix (Type II). Although the formation of LPSO phase can enhance the strength to some extent, it strongly compromises the solid-solution strengthening effect due to the consumption of alloying elements in this alloy.