Evaluation of the Reinforcing Effect of Intermetallic and Ceramic Phases in a WE54-15%(Vol.%)SiCw Composite Using In Situ Synchrotron Radiation Diffraction

The reinforcing effect of β-Mg14YNd2 precipitates and SiC whiskers has been evaluated in a WE54-15%(vol.%)SiCw composite using synchrotron radiation diffraction during compression tests from room temperature to 300 °C. The addition of SiC whiskers slightly increases the yield stress compared to an unreinforced WE54 alloy. However, whiskers are not effective in increasing the temperature at which the mechanical strength of the unreinforced WE54 alloy begins to decay. The plastic deformation process is controlled by the magnesium matrix over the entire compression temperature range. On one hand, β-Mg14YNd2 precipitates assume an additional transferred load from the magnesium matrix just after the yield point in both the WE54 alloy and WE54-15%SiCw composite. The magnitude of transferred load becomes smaller as the temperature increases due to the relaxation process around precipitates. On the other hand, the reinforcing effect of SiC whiskers is greater than that of β-Mg14YNd2 precipitates, although its effect also tends to disappear at temperatures equal to or higher than 200 °C.