Additive manufacturing (AM) is pivotal in advancing in-situ resource utilization (ISRU) technologies for space exploration, enabling the construction of lunar infrastructure directly from local materials such as lunar regolith. Among the various AM techniques, laser-based directed energy deposition (DED-LB) offers scalability and binder-free processing, making it highly suitable for fabricating large-scale components on the Moon. However, the limited availability of actual lunar regolith necessitates the use of simulants. Mullite, an aluminosilicate ceramic with a chemical composition closely resembling that of highland lunar regolith, is a promising candidate. In this study, synthetic mullite with a spherical morphology was employed as a model feedstock to investigate the feasibility of fabricating multilayer 3D printed components using the DED-LB process. The high thermal stability and round particle morphology of mullite make it an ideal proof-of-concept material to understand the thermal and mechanical challenges associated with lunar regolith printing. A combination of in-situ thermal monitoring and microstructural characterization was used to define optimal process parameters and assess print quality. The results demonstrate the suitability of mullite for DED-LB and contribute to the development of scalable AM processes for future lunar infrastructure.

Although Directed Energy Deposition (DED) of Ti–6Al–4V has been widely explored for its mechanical performance, the combined influence of build orientation and surface position (upskin/downskin) on passive film kinetics and fluoride-induced degradation remains largely unexamined. This study addresses this gap by systematically investigating how processing direction and surface thermal history govern microstructure and corrosion behaviour in Laser-Based DED (LB-DED) Ti–6Al–4V. The alloy was fabricated in XY and XZ orientations, and both upskin and downskin surfaces were evaluated. Microstructural characterisation revealed strong anisotropy, with elongated prior-β grains and directional α + β colonies particularly prominent in the XZ orientation. Electrochemical testing in borate buffer showed stable passivity across all conditions, with XY surfaces forming the most compact oxide films. In a more aggressive 2.5% NaF saliva environment, substantial orientation-dependent degradation was observed: XY specimens maintained low corrosion currents and uniform passive layers, whereas XZ downskin exhibited unstable passivation and extensive micro-pitting. These findings demonstrate, for the first time, that the interplay between build orientation and surface position critically dictates passive film defect structure, stability, and fluoride-driven breakdown, providing new mechanistic insight into the corrosion behaviour of DED Ti–6Al–4V relevant to biomedical applications

Nitinol belongs to the class of smart materials that have attracted the attention of researchers in recent decades due to their new promising industrial applications. Because of the austenite/martensite phase transformation, nitinol offers unique properties: superelasticity and shape memory effect. The former ability can be exploited for sensing, actuating, and damping applications. On the other hand, additive manufacturing of nitinol has started kicking off unimaginable applications exploiting the complexity-for-free characteristics offered by the 3D printing processes. Although stand-alone research on additive manufacturing of nitinol is available, the impact of different manufacturing steps, such as machining and heat treatment, on its superelasticity is severely lacking. This work used a powder bed fusion process using a laser beam to manufacture a Ni50.4Ti49.6 austenitic alloy, which was subsequently heat-treated at different aging temperatures. Subsequently, turning operations were carried out at varying cutting speeds under cryogenic cooling conditions. An in-depth characterization of the surface integrity and SE alterations induced by manufacturing was conducted before and after machining. The outcome of the work provides the best combination of heat treatment and machining parameters that allow for maximum surface integrity and SE. .

Corrosion and stress-corrosion related failures often compromise the integrity of critical metallic components during their service, raising significant concerns. It is crucial to comprehend the crack initiation mechanism and the impact of alloy microstructure on this crack initiation process. It is known that the introduction of unique microstructures through metal additive manufacturing brings new challenges. This study aims to investigate, for the first time, the effects of microstructural alterations resulting from fluctuations in laser power during laser powder bed fusion on the surface cracking initiation mechanism and electrochemical behaviour of Ni-Fe-Cr alloy 718, which is widely used in applications that require exceptional strength and corrosion resistance. To carry out this investigation, microcapillary electrochemical methods were combined with high-resolution techniques (TEM, SEM, AFM). The findings emphasize the existence of an optimal range of process parameters that effectively mitigate corrosion and crack initiation susceptibility. This work demonstrated that slight deviations in laser power from this optimal value result in diverse alterations at the micro and submicron scales. These alterations include increased subgrain width, porosity, dislocation density, density of nanovoids, and distribution of carbides. Importantly, these changes, particularly in dislocation and nanovoid densities caused by minor variations in process parameters, significantly affect the material's susceptibility to corrosion initiation and stress-assisted surface cracking.