Influence of the Zr content on the processability of a high strength Al-Zn-Mg-Cu-Zr alloy by laser powder bed fusion

The objective of this research is to study the effect Zr on L-PBF processability, microstructure, and microhardness an AlZnMgCu-Zr alloy. Two AlZnMgCu-0.5 1.5 wt% pre-alloyed powders were produced by casting followed gas atomization. In addition, excess Mg Zn was added target compositions compensate for vaporization during L-PBF. as-atomized as-built heat treated specimens characterized via scanning electron microscopy, backscatter diffraction, transmission microscopy. Crack-free samples with a relative density 99.0 ± 0.1% obtained in alloy containing wt%Zr. microstructure consisted small equiaxed grains without preferred grain orientation near melt pool boundary slightly columnar between adjacent pools. After solution aging treatment (T6), newly developed AlZnMgCu-1.5Zr has outstanding Vickers micro-hardness 223 3 HV, which significantly higher than that wrought Al7075-T6 aluminum This excellent mechanical behavior attributed presence large Al3Zr nucleant particles up 500 nm size inhibit growth solidification subsequent treatment, high nanoscale second phases (MgZn2 Al3Zr) located within aged ?-Al grains.