Significance of α-Al cellular matrix in tensile behavior and work-hardening of additive manufactured AlSi10Mg alloy

The cellular structure, surrounded by an interconnected Si-rich eutectic network, is prevalent in Al–Si alloys produced through additive manufacturing (AM). While the role of cellular boundaries in mechanical behaviour is well-documented, the impact of the α-Al cellular matrix's mechanical properties on tensile behaviour remains insufficiently explored. This study methodically examines the characteristics of the α-Al cellular matrix and its contributions to tensile behaviour in AlSi10Mg alloy samples fabricated using laser-directed energy deposition (L-DED). Findings reveal that the α-Al cellular matrix contributes approximately 80% to the yield strength of the L-DED AlSi10Mg alloy. The back stress and effective stress generated by the cellular matrix contribute to the flow stress, significantly enhancing the work-hardening capability, thereby achieving greater strength and elongation. Intriguingly, augmenting the strength of the cellular matrix not only boosts the tensile strength but also postpones the onset of damage nucleation, thus enhancing ductility. Our research highlights the pivotal role of the cellular matrix in tensile behaviour, providing crucial insights that enable precise manipulation of microstructures and properties in AM-produced Al–Si alloys to meet diverse application demands. The significance revealed in this work is expected to be also applicable to other alloys that commonly have cellular structures in AM process.