Microstructure, mechanical performance, and corrosion behavior of additively manufactured aluminum alloy 5083 with 0.7 and 1.0 wt% Zr addition

Effect of 0.7 wt% and 1.0 wt% of Zr alloying on the laser powder bed fused (LPBF) printability/buildability of AA5083 alloys was investigated by examination of the microstructure and mechanical property. General corrosion behavior of these Zr-modified AA5083 alloys produced by LPBF in 3.5 wt% NaCl solution was also examined and compared to the LPBF AlSi10Mg alloy and AA5083-H131 alloy. Unmodified AA5083 alloy produced by LPBF exhibited extensive solidification cracks, but alloying it with Zr mitigated the cracking due to the grain refinement from the formation of the primary L1₂-Al₃Zr. Moreover, 1.0 wt% of Zr alloying broadened the LPBF processing window compared to the 0.7 wt% of Zr alloying. This slightly higher Zr alloying content also increased the yield strength and enhanced the age-hardening behavior of the LPBF Zr-modified AA5083 alloy. Transmission electron microscopy verified the primary Al₃Zr in the as-built alloys responsible for grain refinement, and the secondary Al₃Zr after aging for precipitation hardening. The corrosion resistance of both LPBF Zr-modified AA5083 alloys was superior to the LPBF AlSi10Mg and wrought AA5083 alloys, as evidenced by the smaller corrosion current density, larger impedance, and less corroded surface after 168 h of immersion. Minor Zr alloying to AA5083 is an effective approach for designing corrosion-resistant aluminum alloys suitable for LPBF additive manufacturing technology.