## 4 PBF-LB/M Process
### Design
#### 4.1.1 Novel Lightweight Compositions
Following this approach, the Elementum 3D metal powder portfolio includesmodified compositions such as Al6061+RAM and Al7050+RAM, in which ceramic nanoparticles like TiB\({}_{2}\), Zr, and TiC are incorporated into the Al-based traditional alloys to improve printability [85]. In addition to modifications to traditional compositions, another approach that can be undertaken to improve processability for PBF-LB/M without incurring hot cracking and other detrimental phenomena while improving the material performance in extreme conditions is the formulation of tailored compositions. Among the Al-based compositions specifically developed for the PBF-LB/M process, the patented Scalmalloy (an Al-Mg-Sc alloy) and A20X (an Al-Cu-Ti alloy) stand out. Scalmalloy, developed by APWORKS, is a high-performance alloy that combines exceptional strength, ductility, and corrosion resistance with low density, making it ideally suited for aerospace, automotive, and other sectors where weight reduction and structural integrity are critical [86]. Sc has a significant impact on the properties of aluminum alloys through its effectiveness as an inoculant, which enhances the formation of fine-grain structures [87]. Additionally, it forms a limited-solubility eutectic diagram with aluminum. Upon cooling, the high-temperature Al-Sc solid solution can decompose, generating finely dispersed and fully coherent Al\({}_{3}\)Sc intermetallic precipitates. These precipitates are notably effective in inhibiting recrystallization, even at elevated temperatures [88]. In addition, Scalmalloy ultrafine and nanoscale microstructure proved to result in exceptional strength and ductility, as well as impressive fatigue resistance [89]. The A20X alloy, developed by Aeromet International, is an advanced aluminum-copper (Al-Cu) alloy system enhanced with TiB\({}_{2}\) nanoparticles for grain refinement. Initially engineered for casting applications, A20X has demonstrated exceptional mechanical properties, including superior strength and fatigue resistance. In response to the increasing demand for high-strength, lightweight materials in the aerospace and defense sectors, Aeromet successfully optimized A20X for PBF-LB/M, enabling the production of complex, high-performance components [90]. Recently, Constellium launched Ahead(r), a new generation of high-performance aluminum powders designed for the PBF-LB/M process. Among these, Ahead(r) CP1 is ideal for high-conductivity applications, while Ahead(r) HT1 is perfect for high-temperature applications [91]. CP1 is an innovative Al-Fe-Zr alloy that exhibits excellent processability, high yield strength, and improved thermal conductivity following direct aging. The formation of primary Al3 Zr prevents hot cracking, while direct aging induces the dual precipitation of coherent nano-Al3 Zr and plate-like Al13 Fe4, boosting the yield strength. Furthermore, the reduction of the supersaturated matrix achieved through PBF-LB/M leads to a simultaneous increase in conductivity [92; 93]. Ahead(r) HT1 is an Al-Mn-Ni-Cu-Zr alloy specifically engineered for PBF-LB/M applications requiring high strength and service temperatures up to approximately 260 \({}^{\circ}\)C. Its excellent thermal stability makes Ahead(r) HT1 an ideal substitute for AA2 xxx aluminum-copper high-temperature alloys. Additionally, it opens up new design opportunities by leveraging aluminum high thermal conductivity and low density, allowing it to be used in service conditions that traditionally require titanium or steel [91]. Table 2 shows some examples of aluminum alloys suitable for PBF-LB/M.