This paper addresses the effects of Ce-rich mischmetal on the microstructure evolution of a 5182 aluminum alloy during annealing and rolling processes. The Ce-rich mischmetal was added to an as-cast 5182 aluminum alloy in an induction furnace, and this was followed by homogenized annealing at 450 °C for 24 h and a rolling operation. The microstructure evolution and mechanical properties’ analysis of the 5182 Al alloy were characterized. The results show that the Ce-rich mischmetal could modify the microstructure, refine the α-Al grains, break the network distribution of Mg₂Si phases, and prevent Cr and Si atoms from diffusing into the Al₆(Mn, Fe) phase in the as-cast 5182 Al alloys. Ce-rich mischmetal elements were also found to refine the Al₆(Mn, Fe) phase after cold rolling. Then, the refined Al₆(Mn, Fe) particles inhibited the growth of recrystallization grains to refine them from 10.01 to 7.18 μm after cold rolling. Consequently, the tensile strength of the cold-rolled 5182 Al alloy increased from 414.65 to 454.34 MPa through cell-size strengthening, dislocation density strengthening, and particle strengthening. The tensile strength of the recrystallization annealed 5182 Al alloy was increased from 322.16 to 342.73 MPa through grain refinement strengthening, and this alloy was more stable after the recrystallization annealing temperature.

This paper systematically investigates the effect of the Ce modifier on the microstructures and mechanical properties of as-cast 5182 Aluminum alloy. The experimental results indicate that the mechanical properties of the alloy are significantly improved after modification, e. g., the tensile strength increases from 248 MPa to 288 MPa, and the corresponding elongation also enhances from 9.7% to 21.9%. One can attribute the main modification mechanism for the property- enhancement to the microstructural optimizations such as grain refinement, solid-solubility, and second phase variation. The Ce not only refines the grain size of as-cast 5182 Aluminum alloy from 109 μm to 25 μm but also reduces the second phases precipitated near the grain boundaries. Reasons for increased tensile strength are both grain refinement and solid solubility improvement. The increase in elongation is due to the grain refinement and the decrease of the second phases particles precipitated along the grain boundary.