Microstructure and Mechanical properties of a Novel Al-5.7Mg-Mn-Sc-Zr-Er alloy
Industrial use of Sc-containing aluminum alloy is so far limited to a few aerospace applications and to sporting equipment, further use is dependent on a price reduction of scandium. However, with this results achieved by lower concentrations of Sc; the use of Al-Mg-Mn alloys may be broaden to other industrial products extensively for automotive applications. An Al-5.7Mg-0.4Mn-0.12Sc-0.1Zr-0.38Er (mass fraction, %) alloy ingots were prepared using resistance furnace. The influence of Er addition on microstructure and mechanical properties of the hot/cold rolling sheet was studied. The significant refinement of as-cast grain size from 290 μm to 90 μm was demonstrated by light microscopic analysis as shown in Figure 1. In Figure 2: a) SEM image, b) XRD analysis and c) EDX line element analysis of Al-5.7Mg-0.4Mn-0.12Sc-0.1Zr-0.38Er show the formation of Al3Er and ternary phases (Al,Mg,Er) with Er addition. The peak hardening effect was obtained after annealing at 370 °С for 4-10 hours with a maximum value of 30 HV. Highest level of mechanical properties was established after rolling with higher amount of cold deformation. Table: 1 demonstrate the mechanical properties of 1570 and 1570 (0.12Sc+0.38Er) alloy. Within as rolled condition the obtained values of UTS, YS and El, are 524 MPa, 480 MPa and 4.2%, respectively and by subsequent annealing at 200 °С for 1 h, the alloy can obtain the optimum application values of UTS, YS and %El, which were 470 MPa, 370 MPa and 9.5%, respectively.