Effect of Ce and Zr on the microstructure and mechanical properties of high-Mg content Al-Mg alloy

Al-7Mg alloy with different Ce and Zr additions were hot and cold rolled to investigate the effects of chemical composition and rolling route on the microstructure and mechanical properties of high-Mg content Al-Mg alloys. The Ce and Zr additions led to the formations of Al11Ce3 and Al3Zr phases in Al-7Mg alloy, and the Zr atoms can be absorbed into the Al11Ce3 phases. The Al11Ce3 phases can be refined by rolling, and the fragmented Al11Ce3 and Al3Zr precipitate phases enhanced the density of dislocations in the studied alloys during rolling. The Al11Ce3 and Al3Zr phases promoted the grain refinement of hot-rolled Al-7Mg-Ce-Zr alloys, but some coarse grains were obtained in the Zr-containing alloys after cold rolling. The rolled alloys with 0.2Ce and 0.25Zr additions own higher second phase and dislocation strengthening effects than the Al-7Mg and Al-7Mg-Ce alloys with the same state, and the yield strengths of the hot-rolled and cold-rolled Al-7Mg-0.2Ce-0.25Zr alloys reach to 242 MPa and 499 MPa, respectively. Furthermore, the ductility of the cold-rolled Al-7Mg-0.2Ce-0.25Zr alloy was improved by its bimodal grain structure.