Evaluation by nanoindentation of the influence of heat treatments and the consequent induced microstructure on the mechanical response of the heattreated L-PBF AlSi10Mg alloy

The hierarchical microstructure of the AlSi10Mg alloy produced by the Laser-based Powder Bed Fusion (L-PBF) determines peculiar microstructural and mechanical characteristics. The scientific literature reports generic correlations between the main microstructural features and the mechanical behavior of the alloy, bypassing however the analysis of the effects of the sub-structure on the local mechanical behavior. The present study, therefore, used the nanoindentation technique to determine the influence of different heat treatment conditions on the sub-structure and local mechanical properties of the L-PBF AlSi10Mg alloy. In particular, the following heat treatments were considered: T5 (160 °C for 4 h), T6B (540 °C for 1 h + 160 °C for 4 h), and T6R (510 °C for 10 min + 160 °C for 6 h). The study highlighted how small variations in the morphology or size of the main microstructural characteristics affect the local mechanical behavior, consequently reflecting on the overall mechanical behavior of the material.