Microstructure and mechanical properties of gadolinium-and misch metal-added Mg-Al alloy

The study investigates the effects of individual and combined additions of gadolinium(Gd)and misch metal(MM)on the microstructure and mechanical properties of Mg-4Al and Mg-9Al alloys.The results show that the additions significantly alter the microstructure and grain size of the base alloys.Mg-4Al based alloys have globular morphology,whereas Mg-9Al based alloys have dendritic morphology.The addition of alloying elements,Gd and MM,introduces rectangular-shaped Al_(2)Gd phase and needle-shaped Al_(11)RE_(3) phase,respectively.The best mechanical properties at room temperature are shown by Mg-9Al-2Gd alloy with tensile strength and elongation of 214 MPa and 6.0%,respectively,whereas Mg-4Al-2Gd alloy exhibits the best properties at elevated temperature(150℃)with tensile strength and elongation of 172 MPa and 14.0%,respectively.The study also reports the microhardness value of different phases along with the cast alloys.Eutectic Mg_(17)Al_(12) phase shows the highest hardness(VHN 92)followed by lamellar Mg17Al12(VHN 83)andα-Mg matrix(VHN 68).