Wire arc additive manufacturing of Al-Mg-Sc alloy: An analysis of the effect of Sc on microstructure and mechanical properties

Al-Mg-Sc alloy was deposited by wire arc additive manufacturing (WAAM). The influence of Sc on the microstructure and mechanical properties of deposited alloys was studied. The results show that supersaturated solution Sc precipitated as Al₃Sc phase during deposition due to the WAAM thermal cycle. After the addition of Sc, a transformation from columnar grains to equiaxed grains occurred in the deposited Al–Mg alloy, accompanied by a significant reduction in grain size. The mechanical properties improved due to the change of the grain morphology and grain size refinement. In addition, the microstructure of the deformation sample shows that the uniformly dispersed Al₃Sc particles hinder the dislocation motion. It means that precipitation strengthening also improves the mechanical properties of deposited Al-Mg-Sc alloy. The yield strength, ultimate tensile strength, and elongation of the deposited Al-Mg-Sc alloy are 183.03 MPa, 335.58 MPa, and 22.74%, respectively. Compared with the deposited Al–Mg alloy without Sc, it increased by 88%, 55%, and 46%, respectively.