Microstructure, tensile properties and heat-resistant properties of selective laser melted AlMgScZr alloy under long-term aging treatment

Selective laser melting (SLM)-processed AlMgScZr alloy has aroused widespread interest in the aerospace industry due to its outstanding comprehensive performance and excellent heat resistant properties. The fine grain morphology and diffusely distributed thermally stable precipitates of this alloy are believed to play a critical role in its high-temperature performance. By modifying the alloy with Sc and Zr, nano-sized Al-3(Sc, Zr) phases can act as heterogeneous nucleating particles to effectively promote grain refining and precipitate strengthening. In this paper, a Sc and Zr-modified Al-Mg alloy was printed by SLM, and the long-term aging treatments in the temperature range of 275-350 degrees C with a constant holding time of 144 h were performed to investigate the heat resistant properties of this alloy. Under as-fabricated condition, the AlMgScZr alloy exhibited high tensile strengths of 487.7 MPa and 393.9 MPa at temperatures of 25 degrees C and 200 degrees C, respectively. When the alloy was aged at 300 degrees C for 144 h, its grain morphology was almost unchanged, but its tensile strength and elongation at room temperature reached 501.3 MPa and 31.3%, respectively.