Metallurgical and Tensile Properties of a Laser Powder Bed Fused Scandium-free Al-Mg-Zr Alloy

In this study, an Al-Mg-Zr alloy was developed for laser powder bed fusion (LPBF) to fulfill the need for a cost-effective, high-strength additive manufactured (AM) aluminum alloy. To get to the peak strength a single-step aging treatment (6 h at 400 degrees C followed by gas quench) was conducted on the printed alloy. The quasi-static uniaxial tensile properties of aged LPBF Al-Mg-Zr were measured as yield strength (YS) of 390 +/- 2 MPa, ultimate tensile strength (UTS) of 428 +/- 2 MPa, and elongation to failure (EL) of 14.26 +/- 0.94 %. Microstructure analyses via scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) displayed the presence of precipitates and a bimodal grain distribution with ultrafine (similar to 1 mu m) and fine grains (similar to 5 mu m). Detailed investigation through transmission electron microscopy (TEM) showed frequent precipitation of nanoscale L1(2)-Al3Zr along with sub-micron Mn- and Fe-rich precipitates (i.e., orthorhombic Al-6(Mn, Fe)) and nanoscale Mg- and O-rich particles. The work-hardening behavior of the studied LPBF Al-Mg-Zr alloy offered valuable insights into the connection between the microstructure and tensile properties.