Search Results (148)

The research investigated the influence of laser powder bed fusion (LPBF) parameters for NickelAlloy HX, a nickel-based superalloy, to achieve high-density components with superior mechanical properties. A systematic approach was employed, involving printing 40 cylindrical specimens with varying energy densities (50–240 J/mm³) to evaluate porosity, hardness, and anisotropy. Results revealed that energy density significantly influences relative density, with optimal parameters identified at 111 J/mm³ (900 mm/s scan speed, 120 W laser power). Microstructural examination revealed columnar grains aligned with the build direction in as-printed samples. The findings highlight the trade-offs between density, hardness, and microstructure in the additive manufacturing of nickel-based superalloys, providing actionable insights for industrial applications requiring specific property profiles. Full article

Nickel-based coatings have been demonstrated to effectively enhance the surface performance of stainless-steel components. The present study investigates the deposition efficiency and quality of Colmonoy 227-F nickel alloy coatings on AISI 304 stainless steel using direct energy deposition (DED). The work focuses on the relationships between process parameters, microstructural features, and mechanical properties. A total of sixteen process parameter combinations were studied, varying laser power and scanning speed to establish optimal deposition conditions and to evaluate coating morphology, surface topology, dilution behavior, and mechanical performance. The surface geometry was analyzed using three-dimensional digital confocal microscopy. New material distribution (MD) indices were developed to quantify spatial uniformity and integrity of single coating scan tracks (CSTs) across the XY, XZ, and YZ planes. The optimal process was identified around 900 W laser power, balancing deposition efficiency and structural integrity. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) reveal a gradual compositional transition between coating and substrate. The results of the microhardness test demonstrate a consistent gradient in mechanical properties, extending from the coating to the substrate. Coatings were found to achieve a hardness level of up to 600 HK. These findings establish a new benchmark for evaluating DED high-performance coatings and offer a scalable methodology for optimizing additive manufacturing processes in surface engineering applications. Full article

Laser additive manufacturing offers significant advantages for fabricating and repairing complex components. However, the complex solidification and remelting processes in nickel-based superalloys for additive manufacturing can introduce defects such as voids and cracks. Therefore, process parameters are crucial, as they significantly impact solidification and remelting, thereby affecting defect formation. In this study, laser-directed energy deposition was employed to evaluate the effects of our key process parameters on the formation of voids and cracks in a novel superalloy. The findings reveal that laser power and linear energy density significantly influence the void content and crack density. However, the influence of other process parameters on defect formation is relatively minimal. The optimal parameter space is characterized by a laser power range of 600~700 W, a linear energy density range of 60~90 J/mm and a powder feeding rate of 0.7~0.8 rpm. Moreover, the precipitation of fine MC-type carbides near the dendrites and grain-boundary misorientations within the range of 31~42° are associated with a higher propensity for crack formation. These insights provide a valuable reference for controlling the process parameters and understanding the cracking mechanisms in laser additive manufacturing of superalloys. Full article

The corrosion behavior of Inconel 718 alloy, developed through two different methods—forging (S1) and additive manufacturing (S2)—was evaluated in a seawater environment, and the results were compared with those of Inconel 825 alloy (S3). The corrosion performance of the alloys was examined according to ISO 8044/2024, using open circuit potential (OCP), potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS), in natural seawater at 25 °C over an extended immersion period. After 5000 h of immersion, the corrosion rate (R_corr) estimated from anodic polarization tests was found to be lower for the wrought Inconel 718 alloy (1.21 µm y⁻¹) compared to the wrought 825 alloy (4.1 µm y⁻¹) and to the SLM Inconel 718 alloy (35.1 µm y⁻¹), indicating high corrosion resistance for wrought Inconel 718. A morphological analysis of the alloy’s surface conducted using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed a continuous, compact film with localized salt deposits on wrought Inconel 718 and Incoloy 825. In contrast, SLM Inconel 718 exhibited a porous, inhomogeneous film, leading to reduced protective capabilities and lower corrosion resistance. The results demonstrate that wrought Inconel 718 exhibits excellent corrosion resistance in seawater, making it a promising alloy for marine applications. Full article

Ferritic stainless steels (FSSs) have attracted considerable attention due to their excellent corrosion resistance and significantly lower cost compared with nickel-bearing austenitic stainless steels. However, the high-temperature wear behavior of additively manufactured FSS 430 has not yet been thoroughly investigated. This study aims to examine the microstructural characteristics and wear properties of laser powder directed energy deposition (LP-DED) FSS 430 fabricated under varying laser powers and hatch distances. Wear testing was conducted at 25 °C and 300 °C after subjecting the samples to solution heat treating at 815 °C and 980 °C for 1 h, followed by forced fan cooling. For comparison, an AISI 430 commercial plate was also tested under the same test conditions. The microstructural evolution and worn surfaces were analyzed using SEM-EDS and EBSD techniques. The wear performance was evaluated based on the friction coefficients and cross-sectional profiles of wear tracks, including wear volume, maximum depth, and scar width. The average friction coefficients (AFCs) of the samples solution heat treated at 980 °C were higher than those treated at 815 °C. Additionally, the AFCs increased with hatch distance at both testing temperatures. A strong correlation was observed between Rockwell hardness and wear resistance, indicating that higher hardness generally results in improved wear performance. Full article

Reducing structural mass and volume is critical to improving efficiency and payload capacity in next-generation small satellites and CubeSats. Additive manufacturing, particularly material extrusion, offers design flexibility and enables the production of lightweight, functional metallic components. This study investigates the integration of nickel–titanium shape memory alloy wires into aluminum-based matrices using a sinter-based material extrusion process, aiming to develop compact actuator systems for aerospace applications. A customized AlSi7Mg aluminum alloy feedstock was extruded into filament form, printed, and embedded with shape memory alloy wires, allowing consolidation during sintering. X-ray micro-computed tomography was used to analyze internal defects and matrix–wire interfacial contact, before and after sintering. Tensile testing of the embedded actuator structures revealed effective mechanical bonding and actuation behavior. The results demonstrate that controlled shrinkage and interfacial bonding enable reliable embedding of shape memory elements without compromising structural integrity. This work provides a promising framework for developing multifunctional aerospace components, where active actuation and structural efficiency can be combined through advanced material extrusion-based manufacturing. Full article

This study investigates the microstructure and mechanical properties of Inconel 718, a nickel-based alloy, reinforced with ceramic phases via additive manufacturing. Two reinforcement strategies were explored: in situ formation of ceramic phases through titanium powder addition, and direct incorporation of Cr₂O₃ and TiO₂ ceramic particles. Both approaches significantly modified the alloy’s microstructure and elemental distribution. The in situ formation method produced leaf-like Ti-rich precipitates (up to 70.13 wt%), while direct ceramic addition suppressed the preferred orientation of the Laves phase and promoted the formation of NbC precipitates. Microhardness increased by 19.4% with titanium addition, compared to a modest 1.3% improvement with direct ceramic addition. Tensile testing revealed that titanium powder enhanced ultimate tensile strength but reduced elongation, whereas direct ceramic addition led to decreases in both strength and ductility. Wear resistance evaluation showed that direct ceramic addition yielded superior performance, evidenced by the lowest friction coefficient (0.514) and smallest wear volume (16,290,782 μm³). These findings demonstrate the effectiveness of ceramic reinforcement strategies in optimizing the mechanical and tribological behavior of additively manufactured Inconel 718, and offer valuable guidance for the development of wear-resistant components such as those used in hydraulic support systems. Full article

The present study aims to investigate the microstructural evolution and local mechanical properties of an AlFe18Si8Cr5Ni2 alloy processed via Powder Bed Fusion–Laser-Based Manufacturing (PBF-LB/M). Designed with a focus on sustainability, this alloy was produced by deriving the necessary elements from AlSi10Mg and 304L steel, two of the most widely used alloys and, consequently, among the easiest materials to source from machining scrap. By leveraging iron, chromium, and nickel from these widespread standard compositions, the alloy mitigates the detrimental effects of Fe contamination in Al-based alloys while simultaneously enhancing mechanical performance. A comprehensive investigation of the impact of rapid solidification and thermal cycling offered novel insights into phase stability, elemental distribution, and local mechanical behavior. In particular, microstructural analyses using scanning electron microscopy (SEM), field emission SEM, energy-dispersive X-ray spectroscopy, X-ray diffraction, and differential scanning calorimetry revealed significant phase modifications post PBF-LB/M processing, including Fe-rich acicular phase segregation at melt pool boundaries and enhanced strengthening phase formation. In addition, nanoindentation mapping was used to demonstrate the correlation between microstructural heterogeneity and local mechanical properties. The findings contribute to a deeper understanding of Al-Fe-Si-Cr-Ni alloy changes after the interaction with the laser, supporting the development of high-performance, sustainable Al-based materials for PBF-LB/M applications. Full article

Masked cold spray additive manufacturing (CSAM) is investigated for fabricating nickel-based electrodes with pyramidal pin-fins that enlarge the active area for the hydrogen-evolution reaction (HER). To bypass the high cost of purely CFD-driven optimization, we construct a two-stage machine learning (ML) framework trained on 48 high-fidelity CFD simulations. Stage 1 applies sampling and a K-nearest-neighbor kernel-density-estimation algorithm that predicts the spatial distribution of impacting particles and re-allocates weights in regions of under-estimation. Stage 2 combines sampling, interpolation and symbolic regression to extract key features, then uses a weighted random forest model to forecast particle velocity and temperature upon impact. The ML predictions closely match CFD outputs while reducing computation time by orders of magnitude, demonstrating that ML-CFD integration can accelerate CSAM process design. Although developed for a masked setup, the framework generalizes readily to unmasked cold spray configurations. Full article

The increasing adoption of electric vehicles (EVs) has highlighted the need for sustainable lithium-ion battery (LIB) management. This study presents a material flow analysis (MFA) of EV LIBs in the Republic of Korea (RoK), using both a mass-based MFA and a substance flow analysis (SFA). The analysis defines 33 systems and 170 flows across the manufacturing, consumption, discharge and collection, and treatment stages, based on national statistics and data from 11 commercial facilities. In 2022, about 72,446 t of EV LIBs entered the consumption stage through new vehicle sales and battery replacements. However, domestic recovery was limited, as approximately 76.5% of used EVs were exported, reducing the volume of batteries available for recycling. The SFA, focusing on nickel (Ni), cobalt (Co), manganese (Mn), and lithium (Li), showed recovery rates of 69% for Ni, 80% for Co, 1% for Mn, and 80% for Li. Mn was not recovered because its low market price made the recovery process economically impractical. Additional losses occurred from the incineration of separators containing black mass and lithium discharged through wastewater. These findings offer data-driven insights to improve recovery efficiency, guide policy, and enhance the circularity of EV LIB management in the RoK. Full article

GH4099 is a nickel-based, high-temperature, precipitation-strengthened alloy with excellent mechanical properties and corrosion resistance, widely used in aerospace components. The performance of parts produced by additive manufacturing depends significantly on alloy powder quality and heat treatment. In this study, GH4099 alloy powder was prepared using the EIGA method, and its morphology, particle size distribution, and flowability were analyzed. The mechanical properties and microstructure of parts before and after solution-aging treatment were compared. Results showed that the powder had good sphericity and flowability, with a median diameter D50 of 28.88 μm. The formed parts underwent solution treatment at 1140 °C for 2 h followed by aging at 850 °C for 8 h. After heat treatment, the transverse tensile strength increased to 1122.11 MPa (+15.1%) and the yield strength to 866.56 MPa (+22.3%), while the longitudinal tensile strength reached 1116.81 MPa (+29.4%) and the yield strength 831.61 MPa (+35.2%). This improvement is attributed to the precipitation of γ′ phase. Fractographic analysis revealed a mixed fracture mode characterized by ductile dimples and cleavage facets, indicating that the alloy exhibits favorable toughness-related features under mechanical loading. These findings demonstrate the excellent microstructure and mechanical performance of GH4099 alloy in AM applications, providing a basis for its further use in high-performance aerospace components. Full article

CuCrZr/GH4169 multi-material structures combine the high thermal conductivity of copper alloys with the high strength of nickel-based superalloys, making them suitable for aerospace components that require efficient heat dissipation and high strength. However, additive manufacturing of such dissimilar metals faces challenges, with each laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) process having its limitations. This study employed an LPBF-LDED integrated additive manufacturing (LLIAM) approach to fabricate CuCrZr/GH4169 components. CuCrZr segments were first produced by LPBF, followed by LDED deposition of GH4169 layers using optimized laser parameters. The microstructure, composition, and mechanical properties of the fabricated components were analyzed. Results show a sound metallurgical bond at the CuCrZr/GH4169 interface with minimal porosity and cracks (typical defects at the interface), achieved by exceeding a threshold laser energy density. Elemental interdiffusion forms a 100–200 μm transition zone, with a smooth hardness gradient (97 HV0.2 to 240 HV0.2). Optimized specimens exhibit tensile failure in the CuCrZr region (234 MPa), confirming robust interfacial bonding. These findings demonstrate LLIAM’s feasibility for CuCrZr/GH4169 and underscore the importance of balancing thermal conductivity and mechanical strength in multi-material components. These findings provide guidance for manufacturing aerospace components with both high thermal conductivity and high strength. Full article

Binder jetting is the most widely implemented additive technology for the fabrication of sand molds. However, the use of furan binder-jetting technology in the production of molds for vacuum casting is hindered by the thermal destruction of the furan binder accompanied by violent gas emission that occurs during the mold heating process. This investigation explores the potential of using the molds obtained via furan binder jetting 3D printing and further impregnation in colloidal silica binder and sintering. Two distinct sands, proppant and cenosphere, were utilized in the fabrication of the mold components exhibiting different thermal properties. An examination of the structure of the initial sands and samples produced via different impregnation and sintering regimes was conducted via scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometry, thermogravimetric analysis, and micro computed tomography. Furthermore, the bending mechanical properties and linear shrinkage of the samples were determined. The experimental findings demonstrated that the specific impregnation and sintering regimes examined in this study yielded sufficient mechanical properties for the casting molds and the structure with cristobalite bridges. The mold assembly, composed of proppant and cenosphere sands-based parts, was produced, and impeller nickel-based superalloy castings were fabricated. The findings of this study demonstrate that the utilization of a furan binder-jetting technique, in conjunction with impregnation in colloidal silica binder, is a promising technology for the manufacture of high-melting-temperature alloy casting. Full article

Inconel 718 (In718) is the most widely used nickel-based alloy in additive manufacturing due to its favorable processability. However, In718’s high-temperature performance is not suited for the most demanding applications in the aerospace industry. Therefore, in this study, Inconel 718 powder was coated with 3% wt. rhenium (In718-Re) using AM’s in situ alloying capabilities to improve high-temperature properties. The proposed alloy’s mechanical performance was evaluated, focusing on the effects of post-process heat treatment and hot isostatic pressing following the laser-based powder bed fusion of metals (PBF-LB/M) processing. Static tensile tests conducted at room temperature and elevated temperatures (650 °C and 760 °C) demonstrated that the alloy has comparable strength to pure In718 according to ASTM F3055-14a—an ultimate tensile strength of 1247 MPa, yield strength of 909 MPa, and almost 2× higher elongation of 23.8%. Fatigue tests at room temperature indicated a fatigue limit below 400 MPa for 10⁷ cycles. Fractographic analysis revealed that fatigue performance was primarily impacted by a lack of fusion defects inherent to the PBF-LB/M process, highlighting the need for optimized powder preparation and processing parameters to minimize defect formation. While rhenium addition shows limited benefits in Inconel 718, this study underscores the potential of in situ alloying through powder surface modification as a flexible method for incorporating high-melting-point elements into nickel-based alloys for tailored alloy design in additive manufacturing. Full article

This study primarily focuses on the analysis of volatile organic compounds using GC–MS, with ICP-MS employed as a complementary method to quantify trace metal content. Headspace GC–MS was conducted to detect alkylphenol ethoxylates (APEOs), formaldehyde, aromatic amines derived from azo dyes, perfluorinated carboxylic acids, chlorophenols (PCPs), tetrachlorophenols (TPCs), and phthalates in textile samples of different origin and composition. Principal component analysis was used to detect patterns in the volatilome according to the origin and the textile composition. In addition, seven metals (Cr, Ni, Cu, Mo, Cd, Hg, and Pb) were quantified in a subset of samples. The study revealed distinct chemical profiles in textiles based on their origin, with GC–MS identifying key volatile organic compounds and ICP-MS quantifying heavy metals in a subset of samples. Principal component analysis highlighted cotton content as a critical factor in differentiating textile profiles. While most samples adhered to regulatory standards, some exceeded thresholds for metals like copper and nickel, underscoring the need for enhanced quality control in manufacturing processes. By integrating advanced analytical methods, this study provides insights into sustainable and safe textile production, offering valuable benchmarks for regulatory compliance and industry best practices. The outcomes contribute to improving product safety, promoting responsible manufacturing, and supporting regulatory bodies in the enforcement of environmental and safety standards, aligning with the growing demand for sustainability in the textile sector. Full article