Effect of Ca and Y additions on oxidation behavior of AZ91 alloy at elevated temperatures

摘要

In order to develop the ignition-proof magnesium alloy,the effect of alloying elements,Ca and Y,on the oxidation behavior of AZ91 magnesium alloy at elevated temperatures was investigated. The ignition-proof performance,oxide products and oxidation kinetics of Ca-and Y-containing AZ91 alloys were studied. The results indicate that the proper addition of Ca can increase the ignition point of AZ91 alloy greatly. However,the oxide film of Ca-bearing AZ91 alloy formed at elevated temperature is thick and brittle,which is prone to crack in melting and cooling process. In addition,the oxide film of AZ91-xCa alloy is incompact and cannot inhibit the diffusion of reaction particles. The oxide film of AZ91-xCa alloy turns to thin and plastic one after Y is added,and the density of the oxide film increases greatly due to the formation of composite oxide film composed of MgO,CaO and Y2O3.