An in-situ synchrotron study of the tensile deformation of LPBF-manufactured AlSi10Mg

This work presents the results of an in-situ synchrotron experiment in which an AlSi10Mg alloy was deformed in tension. The in-situ tensile test was conducted on a miniaturized dog-bone specimen at the MAX IV synchrotron facility (Lund, Sweden). The DanMax beamline was used to scan the specimen and allowed for a spatial resolution of ~250 nm per voxel. A customized tensile rig was used, and multiple scans were acquired to image the entire gauge volume. The specimen was fabricated via laser powder-bed fusion (LPBF) and subsequentially annealed at 520°C for about 2 h. Its microstructure consisted of an α-Aluminum matrix in which globular Silicon particles were embedded. In particular, the Si particles had an average particle size less than ≈ 5 µm, and could be spatially resolved by Synchrotron X-Ray tomography. The alloy also contained a small amount of matrix porosity, with most pores having a spherical shape and an average size ranging between ≈ 5‑80 µm. FE-based Digital Volume Correlation (DVC) was then used to assess strain fields at the microscale, using the reconstructed volumes. Various techniques were tailored to this specific application, including the use of adapted meshes consistent with the final crack geometry, and the stitching of reconstructed volumes (acquired at different heights) via integrated-DVC. Damage mechanisms leading to final failure were quantified based on the evolution of strain results. It is shown that the presence of large defects within the matrix triggered damage accumulation and promoted the formation of a macroscopic crack, which ultimately led to specimen failure. The mechanisms of void nucleation, growth and coalescence were also investigated through the analysis of DVC residuals across the different scans. Last, the microscale strain maps were rationalized on account of the melt-pool geometries revealed by the Si particle distribution.