Realizing superior high-temperature mechanical properties in Laser Powder Bed Fusion Al-Mn-Mg-Sc-Zr alloy via dual-nanoprecipitation strengthening

Abstract

Laser Powder Bed Fusion (LPBF) additive manufacturing technology offers a route for developing high-performance Al alloys. This study utilized LPBF to fabricate Al-Mn-Mg-Sc-Zr alloys, focusing on the high-temperature mechanical properties and fracture behavior. Results indicate that the alloy with bimodal structure exhibits an excellent strength-ductility balance from room temperature to 250 °C, with a yield strength of 512 MPa and an elongation of 12.3 % at room temperature, and a yield strength of 370 MPa and an elongation of 12.0 % at 250 °C. Even at 300 °C, this alloy retains a satisfactory yield strength of 269 MPa. The exceptional high-temperature performance results from the Al₃Sc and Al₆Mn dual-nanoprecipitation strengthening. However, high temperature ductility dip occurs at temperatures above 300 °C due to the coarsening of Al₆Mn precipitates in the fine-equiaxed grain regions. This study provides valuable insights for designing the microstructure of heat-resistant Al alloys used in additive manufacturing.