Effect of Ca content and rheo-squeeze casting parameters on microstructure and mechanical properties of AZ91-1Ce-xCa alloys
(National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: The microstructure, mechanical properties and flame resistance behavior of the AZ91-1Ce alloys with different Ca additions were firstly investigated. Then, the effect of processing parameters, including applied pressures and rotation speeds, on the microstructure and mechanical properties of the rheo-squeeze casting AZ91-1Ce-2Ca alloy was studied. The results indicate that with the increase of Ca content, the microstructure is refined and the flame resistance of the AZ91-1Ce-xCa alloys increases. But when the Ca content exceeds 1 wt.%, with the Ca content increasing, the mechanical properties of the AZ91-1Ce-xCa alloys reduce rapidly. For rheo-squeeze casting process, the increase of applied pressure and rotation speed can both bring about significant refinement in the microstructure of the AZ91-1Ce-2Ca alloy and reduction of the porosity, so the mechanical properties increase. Compared to conventional casting, the AZ91-1Ce alloy with the addition of 2 wt.% Ca by rheo-squeeze casting not only guarantees the oxidation resistance (801 °C), but also improves mechanical properties.
Key words: Ca; AZ91-1Ce alloy; oxidation resistance; rheo-squeeze casting