Microstructure, mechanical properties and fatigue crack growth behavior of an Al-Zn-Mg-Cu-Si-Zr-Er alloy fabricated by laser powder bed fusion.

[Display omitted] • A novel Al-Zn-Mg-Cu alloy with Si-Zr-Er addition was successfully prepared by LPBF. • Precipitates observed in the alloy include Al 2 CuMg, MgZn 2 , Mg 2 Si and Al 3 (Zr,Er). • Transgranular and intergranular modes of fatigue crack growth were both observed. • The fatigue life reached highest under the condition of r = 0.5 and P max = 0.3kN. An Al-Zn-Mg-Cu alloy modified by Si-Zr-Er was prepared by laser powder bed fusion (LPBF), the tensile strength of as-printed alloy reached 445 MPa. Precipitates observed in the alloy included Al 2 CuMg, MgZn 2 , Mg 2 Si and Al 3 (Zr,Er). The accumulated dislocations near the crack tip could combined with the second phases to hinder the propagation of fatigue crack. Transgranular and intergranular modes of fatigue crack growth were both observed in the alloy, and deflection was prone to occur when the crack encountered grains with high misorientation. The fatigue life (N = 1.02 × 106 cycles) reached highest under the condition of r = 0.5 and P max = 0.3kN. [ABSTRACT FROM AUTHOR]