Laser powder bed fusion of Zr-modified Al-Cu-Mg alloy: Processability and elevated-temperature mechanical properties

Zr modification is an effective method for improving hot-cracking resistance and elevated-temperature mechanical properties during laser powder bed fusion (L-PBF) of traditional medium and high strength wrought aluminum alloys. This study investigated the L-PBF processability and elevated-temperature mechanical properties of a Zr-modified 2024Al alloy. It was found that the hot-cracking susceptibility increased with the increased scanning speed, which was in reasonable agreement with the modified Rappaz-Drezet-Gremaud criterion. Furthermore, the primary L1(2)-Al3Zr precipitates, which acted as efficient nucleation sites, precipitated at the fusion boundary of the melt pool, leading to the formation of a heterogeneous grain structure. The yield strength (YS) of the as-fabricated samples at 150, 250, and 350 degrees C was 363, 210, and 48 MPa, respectively. Despite the slight decrease to 360 MPa of the YS when tested at 150 degrees C, owing to the additional precipitate strengthening from the L1(2)-Al3Zr precipitates, the YS achieved yield strengths of 253 and 69 MPa, an increase of 20.5% and 30.4%, when tested at 250 and 350 degrees C, respectively. The yield strengths in both the as-fabricated and T6-treated conditions tested at 150 and 250 degrees C were comparable to those of casting Al-Cu-Mg-Ag alloys and superior to those of traditionally heat-resistant 2219-T6 and 2618-T6 of Al-Cu alloys. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

Zr modification improves the hot-cracking resistance and elevated-temperature mechanical properties of aluminum alloys. The study found that the hot-cracking susceptibility increased with the scanning speed. Zr modification led to the precipitation of primary L1(2)-Al3Zr precipitates and the formation of a heterogeneous grain structure. The yield strength of the Zr-modified alloy showed significant improvement at elevated temperatures, surpassing traditional alloys with good heat resistance.