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Page 6 of 15 Gao et al. J Mater Inf 2023;3:6 https://dx.doi.org/10.20517/jmi.2023.03

Figure 2. Effect of different characteristic variables (i.e., Ed, layer rotation, and test direction) on the mechanical properties of different
SLMed Al-Si-(Mg) alloys: (A), (D), and (G) Al12Si alloys; (B), (E), and (H) AlSi10Mg alloys; (C), (F), (I) Al7SiMg alloys. Ed: energy
density; EL: elongation; UTS: ultimate tensile strength.

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to behave with low tensile strength and weak ductility when the Ed is low (≤ 30~40 J/mm ). Therefore, in
order to design high-performance alloys, some data points with Ed lower than 35 J/mm , especially for
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Al12Si alloy in the lower left region, should be deleted during the data cleaning.

Figure 2D-F and Figure 2G-I show the effect of rotation angle and testing direction on the properties. The
results demonstrate that the UTS and EL of the alloys are much lower when both the rotation angle and the
testing direction are 90°. Moreover, all the high-performance data points occur with a combination of layer
rotation of 67° and test direction of 0°. This fact may be associated with the grain size and combination of
neighboring powder layers during the additive manufacturing process . With an optimal layer rotation,
[23]
the fully densified parts with refined grain size can be fabricated. Meanwhile, directional solidification in
SLM leads to preferential grain growth along the <100> direction, and the resulting intense texture is the
main reason for the anisotropy of the alloy . Thijs et al. found a strong <100> texture along the scanning
[80]
[80]
direction (i.e., parallel to the substrate plane) in SLMed AlSi10Mg alloy. It led to higher UTS and EL in
alloys along the 0° test direction. However, an interesting observation was also found in some literature
reports [12,49,53,54,56,66,68-70,72,74,75] , as shown in Supplementary Figure 1. Under the same preparation conditions, the
[49]
alloys with a test direction of 90° can also exhibit higher UTS. Kimura et al. found the presence of
coarsened microstructure encompassing the borders of laser scan tracks, which led to a lower UTS for
[81]
horizontal alloys. Meanwhile, Kumar et al. discovered that the distribution of molten particles along the
vertical direction has a strong inter-particle bond, which plays a role in enhancing the strength of the alloy,
but also increases the brittle behavior. As a result, they show a higher UTS but with a lower EL compared
with the other alloys. Hence, in the Al-Si-(Mg) alloys, the influence of different features on the alloy
properties is complex, and it is difficult to obtain the ideal target alloy by simple data analysis or limited
experiments.