Influence of Minor RE Addition on Microstructures, Tensile Properties, and Creep Resistance in a Die-Cast Mg–Al–Ca–Mn Alloy

In this work, we have investigated the influence of RE content on the tensile property, creep resistance, and microstructures of a die-cast Mg-9Al-0.3Ca-0.2Mn (wt. %). Minor content of RE elements simultaneously increases the strength and ductility, which is mostly since RE addition refined primary dendritic a-Mg and eutectic a-Mg matrix and eutectic b-Mg17Al12 phases and formed thermally stable Al11RE3 phases. The 0.6% RE adding alloy obtains the best strength-ductility synergy along with the UTS of 245 MPa, TYS of 170 MPa, and EL of 5.7%. The 0.6-1.0% RE addition gives rise to a reduction of the minimum creep rate by over one order of magnitude of the alloy, indicating a significant enhancement in creep resistance, which can be mainly attributed to RE addition introducing Al11RE3 phases to prevent grain boundary sliding, and suppressing dynamic precipitation of g-Mg17Al12 phases during high-temperature creep. These results can provide important references for the design of creep-resistant die-cast Mg alloys and promote the application of commercial Mg-Al based alloys at high temperatures.& COPY; 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-NDlicense (http://creativecommons.org/licenses/by-nc-nd/4.0/).