Microstructure and tensile property of a novel AlZnMgScZr alloy additively manufactured by gas atomization and laser powder bed fusion

Dense and crack-free Al-6Zn-2Mg (wt%) alloys with 1 wt% (Sc + Zr) addition were additively manufactured by laser powder bed fusion (LPBF) using gas atomized powders. As-built microstructure consisted of small equiaxed grains near the melt pool boundary and columnar grains between adjacent melt pools. Alloying of Sc + Zr promoted the formation of Al-3(Sc,Zr) partides, which contributed to the grain refinement. The alloy exhibited outstanding tensile properties (i.e., 418 +/- 3 MPa yield strength, 436 +/- 3 MPa tensile strength and 11 +/- 1% elongation) after heat treatment. The results demonstrate that high strength aluminum alloy can be fabricated by LPBF through alloy design and microstructural control. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.