The effect of LPSO phase on the high-temperature oxidation of a stainless Mg-Y-Al alloy.

• The network-like LPSO phase in a Mg-11Y-1Al alloy decomposed into needle-like LPSO phase and polygonal Mg 24 Y 5 phase. • The in-situ oxidation of the needle-like LPSO phase facilitated the formation of a thicker and continuous Y 2 O 3 oxide scale. • The accelerated oxidation along the needle-like LPSO phase is attributed to divert the parabolic growth kinetics to a slower oxidation rate. In this study, we investigated the oxidation of the Mg-11Y-1Al alloy at 500 °C in an Ar-20%O 2 environment. Multiscale analysis showed the network-like long-period stacking ordered (LPSO) phase transformed into needle-like LPSO and polygonal Mg 24 Y 5 phases, leading to the formation of a high-dense network of needle-like oxides at the oxidation front. These oxides grew laterally along the oxide/matrix interfaces, forming a thicker, continuous scale that effectively blocked elemental diffusion. Hence, the preferential oxidation along the needle-like LPSO is believed to accelerate the formation of a thicker and continuous oxide scale, further improving the oxidation resistance of the Mg-11Y-1Al alloy. [Display omitted] [ABSTRACT FROM AUTHOR]