Microstructure and mechanical property correlation for additively manufactured aluminum-silicon alloys

Aluminum-silicon alloys have become a popular choice for applications in the automotive and aerospace industries and have proven themselves through their fault-tolerant processability and respectable static properties at comparatively low costs. However, these alloys feature unique properties, when processed via laser powder bed fusion (LPBF). Although the finely dispersed silicon precipitates allow achieving fine-grained microstructures leading to superior static properties compared to those of their cast counterparts, they induce directional weak linkages through layered accumulation. This, in turn, reduces shear and crack tolerance and therefore weakens and strengthens the structure at the same point. Consequently, this necessitates a consideration of these effects when designing a part to be manufactured via LPBF. Heat treatments can be an addition to the processing routine and can enhance key properties, such as ductility and fatigue resistance, but generally reduce the static material strength. This chapter addresses these correspondences and sheds light on achievable properties across a wider range, including tensile, compressive, and torsional behaviors, fracture toughness, and fatigue resistance.