Search

Graphical abstract Highlights • Microalloying with Be effectively improved the oxidation resistance of Mg-2Zn, Mg-2Sn, AS21 and ZC63. • Microalloying with Be had little effect on the oxidation resistance of ZK20, AM60 and Mg-2Y. • The oxidation resistance of Mg alloys was closely related to the mechanical strength of the initially formed oxide layers. • The nanoindentation testing provides a new approach to understand the mechanism for the oxidation resistance of Mg alloys. Abstract The present work studied how Be influences Mg alloy oxidation. Be microalloying significantly decreased the oxidation rate at 500 °C and increased the ignition temperatures of as-cast Mg-2Zn, Mg-2Sn, AS21, and ZC63. However, Be addition had little effect on the oxidation resistance of as-cast ZK20, AM60 and Mg-2Y. Based on the nanoindentation results, the present results can be well understood and explained using the recently proposed oxide layer reinforcement model, which indicates that the mechanical strength of the initially formed oxide controls Mg alloy oxidation. [ABSTRACT FROM AUTHOR]

The oxidation resistance of Mg-9Al-1Zn alloy (AZ91) was significantly improved through microalloying with 60 ppm Be. Be reinforced the initially formed oxide layer on the alloy surface by (i) the formation of a (Mg,Be)O solid solution due to the Be enrichment; and (ii) the refined gains of the (Mg,Be)O. During high-temperature oxidation, the reinforced (Mg,Be)O layer provided sufficient strength to withstand the internal stresses and the Mg vaporisation, and therefore delayed the oxide layer cracking and debonding from the substrate. In addition, the initial oxidation rates of AZ91 and Be-containing AZ91 were closely related to surface roughness. [ABSTRACT FROM AUTHOR]