Al-8Fe-4Ce alloy by laser powder bed fusion

Among various additive manufacturing (AM) processes, laser powder bed fusion for metals (PBF-LB/M) has stood out in the last few years as a reliable method for processing aluminum alloys containing transition metals (TMs) and rare earth elements (REEs) as major alloying elements. This is mainly due to the inherent characteristics of PBF-LB/M, namely high cooling rates (103-106 K/s) and the ability to create complex-shaped objects. Al-TM-REE alloys processed by PBF-LB/M are attractive as high strength materials for high temperature applications, as they contain a high-volume fraction of fine thermally stable intermetallic phases. They could replace heavier and more expensive materials (e.g. steel or titanium) when the service temperature does not exceed 573 K. However, limited investigations have been performed on Al alloys characterized by simultaneously high contents of TMs and REEs. Therefore, this study aimed to evaluate the feasibility of processing an Al-8Fe-4Ce (wt%) alloy by PBF-LB/M and its mechanical properties. Initially, different parameter sets were investigated to select the optimal processability window to obtain dense, crack-free samples. Although this proved particularly challenging due to the inherently high fraction of intermetallic phases, crack-free specimens with a relative density exceeding 99% were ultimately obtained. The optimal parameter set was then used to fabricate cubic and tensile specimens. As-built samples were characterized by scanning electron microscopy (FESEM) to investigate the effects of the rapid solidification on the microstructure. Phase identification analysis was performed by X-ray diffraction (XRD), while the thermal stability was evaluated using differential scanning calorimetry (DSC). Nanoindentation and uniaxial tensile testing were employed to assess the mechanical properties of the alloy. Finally, post-mortem analysis was carried out on tested tensile specimens to study the failure mechanisms.