Effect of Nd on Microstructure and Mechanical Properties of Mg-Al-Ca Alloy

The microstructures and precipitated phases of as-extruded Mg-Al-Ca-xNd alloys with x=0 wt%similar to 1.76 wt% Nd were studied by OM, SEM and XRD. The mechanical properties of the alloys at room temperature and high temperature were also tested. Results show that the addition of Nd results in the formation of Al2Nd and Al11Nd3 phases in the matrix and the grain refinement of Mg-Al-Ca alloy, and the amount of Al2Nd and Al11Nd3 phases increases with the increase of Nd addition. The average grain size of these alloys changes from 4.80 gm (without Nd) to 2.39 gm (with 1.76 wt% Nd added). The mechanical properties at room temperature are improved due to the precipitation of the second phases and grain refinement. With increment of Nd, the tensile strength increases from 267 MPa to 304 MPa, the yield strength increases from 144 MPa to 203 MPa and the elongation decreases from 20.0% to 16.9% at room temperature. At 150 degrees C, the tensile strength increases from 192 MPa to 229 MPa, the yield strength increases from 140 MPa to 159 MPa and the elongation decreases from 48.6% to 29.3% with increasing the Nd content.