Microstructure and mechanical properties evolution of Al-Mg-Sc-Zr alloy fabricated by laser powder bed fusion

The densification characterization, phase constitution, precipitation evolution and mechanical performance of Al-Mg-Sc-Zr alloy processed by laser powder bed fusion (LPBF) were systematically investigated. Moreover, the evolution of phase constitution and precipitation behavior after heat treatment were characterized by using X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis. The ultimate tensile strength (UTS) of as-built samples ranged from 396.8 to 414.6 MPa as the scanning speed decreased from 1600 to 1000 mm/s. After post heat treatment, the yield strength (YS) increased to (513.1±1.3) MPa, while the UTS increased from (414.6±5.1) to (539.2±1.5) MPa. The significant improvement of mechanical performance was ascribed to the formation of secondary Al 3 (Sc,Zr) precipitates.