Elevated temperature behaviour of rapidly solidified magnesium alloys containing rare earths

The microstructure and mechanical properties of bars of six magnesium alloys (AZ91, AZ151, ACa54, ZE41, WE43 and WE54) extruded from melt spun ribbons, were investigated. At room temperature, the 0.2% proof stress of all the alloys (300–500 MPa) is much higher than that of commercial cast magnesium alloys. As far as the effect of temperature is concerned, the alloys can be separated into two classes: whereas in the case of AZ91, AZ151, ZE41 and ACa54, the yield stress of the bars decreases rapidly as soon as the temperature increases, it remains very high up to about 150°C in the case of WE43 and WE54, before rapidly decreasing. Furthermore, the creep resistance of WE alloys is far better than that of AZ alloys. The high yield stress at low temperature is ascribed to a strong Hall-Petch effect (mean grain size ∼0.5 μm). The medium and high temperature behaviours are discussed, with emphasis on the particular case of WE alloys.