Mechanical properties and microstructure of Al-Mg-Mn-Zr alloy processed by equal channel angular pressing at elevated temperature

An Al-Mg-Mn alloy containing Zr, and a standard 5083Al alloy were fabricated. The as-cast alloys were homogenized, hot extruded and hot ECAP (equal channel angular pressing). After hot extrusion, the ultimate strength of the Al-Mg-Mn-Zr alloy was 30.0 MPa higher than that of 5083Al, but the elongation was 10.1% lower. This was because the Al3Zr dispersoids in the Al-Mg-Mn-Zr alloy enhanced the strength and inhibited the recovery process during the hot extrusion, but simultaneously decreased the ductility. After hot ECAP, the strength of the Al-Mg-Mn-Zr alloy was still 32.6 MPa higher than that of 5083Al but without significant loss of the elongation. This implied that the fine-grained, high-angle boundaries microstructure produced by hot ECAP can effectively enhance the strength with little compromise of the ductility of the Zr-modified alloy.