Harnessing centrifugal casting for designing aluminum alloys adapted to laser powder bed fusion

Additive manufacturing technologies like laser-based powder bed fusion of metals (PBF-LB/M) enable the fabrication of lightweight, intricate aluminum structures. However, harsh processing conditions drastically limit the processability of alloys. Thus, customized materials must be developed for PBF-LB/M, which is a tedious task. Fast screening methods can facilitate the identification of suitable compositions. Here, gravity casting (CG) with enhanced cooling rates and centrifugal casting (CC) as rapid cooling technique were employed to investigate its suitability as material pre-screening technique. Advantageously, only a small amount of starting elements are needed, no powder is required, and high cooling rates can be applied. By this approach, the influence of a wide range of cooling rates (10 1 – 10 5 K/s) on the microstructure and the mechanical properties of AlSi12 processed by GC, CC and PBF-LB/M was investigated. The microstructure transformed from a degenerated eutectic dispersed with coarse dendritic α-Al (GC) to a fibrous Al-Si eutectic combined with fine dendritic α-Al (CC) up to a cellular α-Al in a heterogenous microstructure (PBF-LB/M). With increasing cooling rates, the average grain size shrank from 198 μm down to 10 μm. Under compressive loading, the 0.2% yield strength (YS) increased at the expense of ductility primarily due to refined grains and changed morphology of Si. Despite a different grain size and YS between PBF-LB/M and CC specimens, the compressive stress of CC specimens at 10% strain reached almost 82% of the strength in PBF-LB/M. Furthermore, the ultimate compressive strength and total strain of PBF-LB/M and CC specimens were almost identical.