Evaluation of microconstituents and influence on the mechanical and tribological behaviour of an Al-Fe-Cr alloy obtained by laser-based powder bed fusion (PBF-LB)

Studies on aluminum-matrix composites are frequent and there are several alternatives for the dispersed phase, including the presence of quasicrystals (QCs) obtained through manufacturing processes that involve melting. Among other effects, QCs can improve wear resistance with respect to other aluminum alloys. The present research considers an additive manufacturing Al‒Fe‒Cr alloy fabricated via Laser-based Powder Bed Fusion of metals (PBF-LB/M). The processing resulted in a composite structure with coarse and fine grain regions along the microstructure, both with dispersed QC particles. The composite was characterized by optical microscopy, scanning electron microscopy, nanoindentation, and scratch tests. In the last case, initial tests with loads increasing from 0 to 100 mN were conducted to understand the transitions between the abrasion mechanisms in both regions. A second set of scratch tests was performed considering constant loads of 20 mN and 80 mN, to better characterize the abrasive micromechanisms. 3D interferometry analyses were performed to identify possible correlations between the mechanical and tribological behavior of each region and the characteristics of the surfaces that resulted from mechanical loading, including metallographic polishing. Results indicate differences in the mechanical and tribological behavior of both regions, but only when low normal loads (e.g., nanoindentation tests with normal loads below 5 mN) were used.