## 1 Introduction  
Additive manufacturing (AM) has gained considerable interest due to its ability to form near-net-shaped components with a high degree of geometric complexity and minimal material waste [1, 2, 3, 4, 5]. The on-demand production made possible by AM promotes design freedom that is not tied down by the constraints of conventional manufacturing [3, 4, 5, 6]. Through additive processing, physical prototyping becomes more feasible [5, 6]. Functional prototypes can be fabricated quickly, effectively eliminating costly and time-consuming fabrication using conventional methods [5, 6]. With the time saved through AM for prototyping, more iterations can be performed, allowing for a more comprehensive design phase. Fabrication via additive technologies also encourages small-volume production, customized parts, and consolidation of existing designs into one comprehensive part, which is impossible with conventional manufacturing [5,6]. AM finds applications in various industries, such as medicine, aerospace, and automotive [7]. Two of the most common AM processes for processing metallic materials are the powder-bed process, selective laser melting (SLM), and the powder-fed process, directed energy deposition (DED). SLM is characterized by the powder bed in which an energy source selectively melts the powder feedstock to form a single layer of a final part [5,8]. After each layer, the powder bed is refreshed, and a new layer is melted to form a fully actualized 3D component [5,8]. SLM is also denoted as direct metal laser sintering (DMLS), direct metal laser melting (DMLM), and laser powder bed fusion (LPBF) [5,7,8]. DED is a commonly used AM technique in which parts are created by melting powder or wire feedstock using an energy source, such as a laser, electron beam, or plasma [5,7,8]. The feedstock material is injected into the melt pool and melted, forming a single layer of a final part [5,8]. The process is continued layer-by-layer until the part is fully fabricated. Depending on the exact method or application, DED is often characterized by various terminology. A few of the alternative terms are laser-engineered net shaping (LENS), direct metal deposition (DMD), and 3D laser cladding [5,7,8]. Currently, a range of materials, such as titanium [9, 10, 11, 12], steels [13, 14, 15, 16], and aluminum [17, 18, 19, 20] alloys, have been implemented with AM techniques. Aluminum is of considerable interest due to its high strength-to-weight and stiffness-to-weight ratios, making it an attractive candidate for use with near-net-shaped processes [21, 22, 23]. Aluminum alloys also exhibit high reflectivity, high thermal conductivity, and a strong tendency to form surface oxides, which negatively impact the AM process and make fabricating these alloys difficult [23]. There is also an issue with the fabrication of high-strength aluminum alloys [24, 25, 26, 27]. When fabricated using AM, high-strength aluminum alloys display a tendency towards crack formation resulting from a wide solidification range [24, 25, 26, 27, 28]. These cracks negatively impact the mechanical behavior and effectively eliminate these highly desired compositions from the options for use with AM [24, 25, 26, 28]. As a result, the only conventional aluminum alloy compositions that directly work with AM fabrication are casting alloys, such as the 4 XXX series Al-Si alloys [24, 25, 26]. While these alloys are easily fabricated with AM, they do not exhibit the desired high-strength properties; thus, alternative avenues have been explored to make AM fabrication of high-strength aluminum alloys possible [25]. Of interest in this study is the avenue of alloy development that works with the unique AM process. Scalmalloy(r) is an Al-Mg-Sc-Zr-based alloy designed for use with the unique thermal profile seen with AM. The high cooling rate of AM processes allows for the potential formation of a supersaturated solid solution (SSSS) [19, 29, 30].