Microstructure and mechanical properties of Al–Zn–Mg–Cu–Er–Zr alloy processed by laser powder bed fusion

Abstract

The preparation of high density Al7000 series Al alloys by laser powder bed fusion (LPBF) is challenging. In this work, a completely crack-free Al–Zn–Mg–Cu–Er–Zr alloy was successfully processed by LPBF. The effect of different laser power and scanning speed on the printability of the alloy was investigated, and the processing window was optimized. By characterizing the microstructure and mechanical properties of the alloy with a density of 99.8 %, it is found that microstructure structure consisting of equiaxed grains at the boundary of the melt pool and columnar grains inside the melt pool. Er and Zr elements participate in the formation of equiaxial grains in the form of Al 3 Er, Al 3 Zr and Al 3 (Er,Zr) phases, which play an important role in inhibiting the epitaxial growth of columnar grains. The as-built alloy achieved an elongation of 17%, with yield strength and ultimate tensile strength of 310 MPa and 368 MPa, respectively.