Al-Fe-Ce alloy processed by laser powder bed fusion: microstructure and mechanical characterization

Laser powder bed fusion for metals (PBF-LB/M) was employed to consolidate an Al-8 þ-4 Î (wt %) alloy originally developed for conventional powder metallurgy processes. This study focuses on the characterization of the as-built microstructure and its mechanical properties at room temperature. Although its high tendency to solid state cracking, crack-free samples with a density of 99.5 % were successfully produced. The as-built microstructure consists of columnar grains, with melt pools containing a high-volume fraction of reinforcing intermetallic phases dispersed in the Al matrix. High-resolution backscattered electron imaging revealed that the melt pool boundary region consists of a cellular structure enriched in Ce and Fe, within which dispersoids are distributed. Conversely, the melt pool center exhibits an ultrafine cellular microstructure. Multiple intermetallic phases were identified using X-ray diffraction, including: the stable phases Al13Fe4 and Al11Ce3 and the metastable Al6Fe. Thermal analyses show the exceptional thermal stability of the alloy at temperatures up to 580 °C. Finally, the alloy exhibits excellent mechanical properties, with an average tensile strength of 530 MPa and an average microhardness of 201 HV0.5. The combination of thermal stability and high strength makes this alloy attractive for applications beyond 200 °C, which can be attributed to the low diffusion alloying elements Fe and Ce.