Single-step additive manufacturing (AM) techniques, such as powder-bed fusion (PBF-LB/M), paved the way for the direct fabrication of ready-to-use metal parts. The direct fabrication of aluminum parts became accessible with the rise of high-power laser setups in AM machines. Especially aluminum–silicon (AlSi) cast alloys became a popular choice and due to the fast quenching in PBF-LB/M, the achieved static mechanical properties surpassed those of the as-cast and heat-treated state. However, certain limitations are present, the most prevalent being the reoccurring weakening in the heat-affected zone surrounding every single scan track, which reduces the overall strength and especially reduces the fatigue performance. Heat treatments can improve fatigue performance, but thereby noticeably reduce the static mechanical strength. Since this limiting factor is tied to the chemical composition of the AlSi alloys, efforts were made to design aluminum alloys for the PBF-LB/M process, which overcome those limitations. This chapter serves to explain the reason the reoccurring weakness is induced in the AlSi alloy family and to explain in which manner this weakness was overcome in aluminum–magnesium–scandium–zirconium alloys.