Additive manufacturing (AM) is a process in which parts are manufactured in a layer-by-layer fashion. Several AM methods have been successfully developed to produce complex geometries and process different materials. Regarding metallic alloys with aerospace applications, directed energy deposition (DED) stands out due to its high deposition rate and superior build quality. Inconel 718 (IN718) is a precipitation-hardened nickel-based superalloy renowned for its exceptional mechanical properties and resistance to oxidation and corrosion at elevated temperatures, up to 650 °C. The alloy derives its strength primarily from the precipitation of γ′ (Ni ₃ (Al, Ti)) and γ″ (Ni ₃ Nb), with additional strengthening from solid solution elements and carbides. Due to its thermal stability, fatigue resistance, and creep performance, IN718 is widely used in aerospace engines, gas turbines, and petrochemical equipment. This work presents a review of IN718-processed via Laser-based DED, exploring recent studies on microstructural evolution, mechanical properties, and post-processing treatments. Graphical abstract

The inhibitory performance of three distinct protic ionic liquids (PILs), namely, 2-hydroxyethyl ammonium formate (PIL 01), 2-hydroxyethyl ammonium propionate (PIL 02), and 2-hydroxyethyl ammonium pentanoate (PIL 03), was evaluated to determine their suitability as eco-friendly corrosion inhibitors for carbon steel (ASTM A36) in a 3.5 wt. % NaCl aerated neutral electrolyte solution. Standard corrosion inhibitor assessment methods, including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), weight loss measurements, and microscopic techniques (SEM and optical microscopy), were employed to examine the steel surface and corrosion rate. There is a general agreement that the inhibition efficacy is directly associated with the adsorption capacity of substances on the surface of an investigated material, normally stainless or carbon steel. The standard free energies of adsorption were approximately −22 kJ mol⁻¹, indicating a physical adsorption type of interaction between ionic liquids and the electrode surface. The adsorption behavior of protic ionic liquids on an A36 steel surface conforms to a Langmuir-type isotherm. In conclusion, PIL 01 demonstrated an inhibition efficiency exceeding 80%, while PILs 02 and 03 exhibited efficacies in the 50–60% range. The inhibition efficiency was observed to be proportional to the inhibitor’s concentration. These results suggest that PIL 01, PIL 02, and PIL 03 exhibit significant corrosion inhibition properties.

Additive manufacturing of Inconel 718 (IN718) produces microsegregation and solidification-induced secondary phases that strongly influence the response to post-processing heat treatments. This study presents a CALPHAD-based modeling framework to predict precipitation kinetics and the resulting mechanical properties of IN718 fabricated by directed energy deposition with a laser beam (DED-LB). Thermodynamic and kinetic simulations were performed in MatCalc to describe the evolution of γ′, γ″, δ, Laves, and MC phases during six industrially relevant heat-treatment routes, including homogenization (H), solution treatment (S), direct aging (DA), and combined sequences (HDA, SDA, and HSDA). The initial microstructure was defined using Scheil-based solidification calculations to represent the microsegregation and solidification-induced phases characteristic of additively manufactured IN718. Simulated phase evolution and yield strength were validated against SEM, EBSD, TEM, EDS, hardness, and tensile data. Aging treatments promoted significant γ″/γ′ precipitation, resulting in hardness values above 480 HV and yield strengths exceeding 1000 MPa, whereas homogenization or solution treatment without aging reduced strength but improved ductility. The model captured the main strength–ductility trends and provided mechanistic insight into the role of Nb partitioning, phase stability, and precipitation kinetics in determining the response of DED-LB IN718 to heat treatment. The proposed framework provides a predictive basis for optimizing post-processing routes in additively manufactured IN718 components.