Melt pool boundaries in additively manufactured AlSi10Mg: Correlating inhomogeneous deformation with local microstructure via in-situ microtensile tests

Microstructures in additively manufactured metals are often inhomogeneous and complex. Melt pool (MP) centers and boundaries can vary significantly, such as in AlSi10Mg, where MP boundaries reveal a coarsening and breakdown of the refined cellular network. However, bulk characterization techniques often lack the resolution to quantify the local deformation on the length scale of a melt pool boundary which ranges from 1 to 100 μm. Here, in-situ scanning electron microscopy (SEM) microtensile experiments on AlSi10Mg samples were used to compare the relative yield behavior and deformation uniformity throughout microstructural regions, particularly around the MP boundaries. Differences in the local mechanical response – deformation, strain hardening, and yield – are reported between the MP boundaries and centers. These differences in deformation are correlated to specific microstructural features like cell size, cell connectedness, cell eccentricity, and grain size. Quantitative correlations of local deformation with relevant microstructural features, as presented here, will aid modelers and the additive manufacturing (AM) community to more precisely predict and control AM AlSi10Mg part performance. [Display omitted] •We quantify the inhomogeneous strains around AM AlSi10Mg melt pools that arise during in-situ SEM microtensile tests.•We correlate the local, inhomogeneous strains with grain size, cell size, cell connectedness, and cell eccentricity.•We estimate the local yield and strain-hardening characteristics for melt pool boundaries and melt pool center regions.•We discuss how melt pool boundaries influence mechanical properties in general and fracture behavior in particular.