Study of the microstructure and mechanical properties of Mg-rare earth alloys

Three kinds of Mg–RE alloys were prepared in the interest of analyzing the influence of the rare earth elements on the mechanical properties in Mg alloys at room temperature and elevated temperature. The microstructure and the phase composition of the three Mg–RE alloys were analyzed by means of optical microscopy, scanning electron microscopy, and X-ray diffraction. It is shown that Mg12Ce, Mg17Ce2, Mg12Nd, Mg24Y5, and Mg41Nd5 distributed mainly along the grains’ boundaries of as-casting alloys. After experimenting on the mechanical properties of these alloys at room temperature and elevated temperature, the results reveal that the tensile strength (σb) of the investigated alloys in as-extruded is higher than that in as-casting. The strengthening effect of Nd is better than that of Ce at room temperature. An experiment performed at 250 °C. The σb of No. 3 alloy is 219.6 MPa which is higher than that of No. 2 alloy (187.3 MPa) and No. 1 alloy (125.6 MPa). The strengthening effect of Nd and Y is better than that of Nd at elevated temperature. It is shown that the strengthening mechanisms of rare earth are different at room temperature and elevated temperature.