Microstructure and mechanical properties of wire-arc directed energy deposited Al-Mg-Sc aluminum alloy: As-deposited and aging heat treated

Abstract

In this study, Al-Mg-Sc aluminum alloys were fabricated using wire-arc directed energy deposition. The focus of the study was to analyze the microstructure and mechanical properties of these alloys. Comparative analysis was conducted on the samples obtained from the as-deposited and aging treated, respectively. Furthermore, the precipitation process of the second phases and the associated strengthening mechanism were elucidated. The findings revealed that the presence of precipitated Al3(Sc,Zr) particles acted as heterogeneous nucleation nuclei of α-Al, facilitating the formation of equiaxial grains. During the subsequent aging treatment, the secondary Al3(Sc,Zr) particles precipitated directly without transitioning through intermediate phases. Additionally, the experimental results demonstrated that these secondary Al3(Sc,Zr) phases hindered the dislocation movement, leading to enhanced mechanical properties in Al-Mg-Sc alloys through precipitation strengthening. In the horizontal direction, the average ultimate tensile strength (UTS) and yield strength (YS) were measured as 361 ± 5 MPa, 251 ± 4 MPa, and 281 ± 6 MPa, 179 ± 6 MPa in the vertical direction, respectively. The elongations were found to be 15.8 ± 0.8% and 4.0 ± 0.5% in the horizontal and vertical directions, respectively. The observed variations in mechanical properties were attributed to the presence of interlayer pores.