Abstract This study investigates the effect of manufacturing parameters on the impact behavior of Charpy test specimens produced from AlSi10Mg alloy using laser powder bed fusion (LPBF) process. For this purpose, specimens were produced using two layer thicknesses (30 µm and 60 µm), two infill patterns (grid and rectilinear), and three scanning angles (0°, 45°, and 90°). The effects of these parameters on impact toughness were experimentally evaluated. V-notched Charpy impact tests were performed, and the absorbed fracture energy (J) and fracture angle (°) were determined. Fracture surfaces were further examined with scanning electron microscopy (SEM) to evaluate pore morphology, dimple formation, and fusion quality. The results show that absorbed fracture energy decreases as the scan angle increases. Ductile fracture was predominantly observed at 0°, while brittle fracture behavior became dominant at 45° and 90°. Increasing layer thickness reduced interlayer bonding quality, leading to lack-of-fusion defects. Accordingly, the 30 µm specimens generally exhibited a denser microstructure and higher absorbed energy (~9 J). The grid (G) infill pattern provided more stable energy absorption compared to the rectilinear (R) pattern. SEM observations clearly demonstrated the effect of processing parameters. In particular, the 30 µm specimens with rectilinear infill, exhibited homogeneous melt pools and distinct dimple formation, indicating ductile fracture. In contrast, the 60 µm specimens showed larger pores, interlayer fusion defects, and directional tearing characteristics. At a scan angle of 90°, fracture surfaces exhibited a more multidirectional character, while at 0° crack propagation was predominantly uniaxial. The highest impact toughness was obtained for the 30-G-0 condition (~9 J), and the lowest for the 30-R-90 condition (~5 J). The findings indicate that LPBF processing parameters have a decisive effect on the impact strength and fracture morphology of AlSi10Mg alloy. These results provide insight into parameter optimization and a better understanding of microstructure mechanical property relationships in components manufactured with LPBF.

Abstract Sandy soils are widely distributed worldwide but are often constrained in geotechnical applications due to their high permeability, low cohesion, and poor load-bearing capacity. This study evaluates the combined stabilization effect of a chemical additive (TX-95) and a soil binder (SB-95) on improving the mechanical and microstructural performance of sandy soils. Laboratory investigations, including Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests, were conducted with varying SB-95 contents under a constant TX-95 dosage and multiple curing periods. The results demonstrated substantial enhancement in strength, with UCS values increasing up to 893 kPa and CBR values rising from 21% to 278%. Through iterative testing, an optimal mixing and curing method was identified that maximized homogeneity and strength gain while minimizing material waste. Scanning Electron Microscopy (SEM) revealed that the optimized process produced dense interparticle bonding through binder films and silane-based bridges, leading to a compact and cohesive soil matrix.Finite Element Analysis (PLAXIS 3D) further validated the experimental outcomes, showing improved stress distribution and deformation resistance of the treated subgrade. The findings confirm that the combined use of TX-95 and SB-95, coupled with the optimized preparation technique, offers an efficient stabilization strategy for sandy soils, making them suitable for durable road subgrades, embankments, and structural foundations.

Abstract In keeping with the transition to a circular bio-economy, chitin as the second most abundant biopolymer and its soluble derivative chitosan are increasingly used to create diverse multifunctional materials. In this work the feasibility of chitin and chitosan derived from mushroom sources as a sustainable, renewable, non-animal, less polluting and energy demanding alternative to crustacean or insect chitin was investigated. A systematic analysis of the structure, morphology, thermal properties of chitin and chitosan derived from: Agaricus bisporus, Pleurotus ostreatus, Pleurotus eryngii, Boletus edulis, Chantarellus cibarius and Cyclocybe aegerita using short alkali and mild acetic acid treatment is presented. The classification artificial neural network concept was applied to measured far infrared reflection spectra of mushroom powder, mushroom derived chitin and chitosan enabling identification of the chitin and chitosan origin. Depending on the fungal species and source (whole, stipes, fresh or dry) chitin and chitosan yields were 8.66 - 15.66% and 5.8 - 50.4%, while crystallinity degrees were 30.45-58.20 and 34.18-65.32%, respectively. The chitin N-acetylation degree was 62.95-95.84%, while the chitosan de-acetylation degree was 85.89 - 96.14%. Noticeable -glucan presence was detected in C. aegerita, P. eryngii and P. ostreatus chitin samples emphasizing the specific advantage of mushroom derived chitin for applications requiring improved flexibility and toughness. Though the antioxidant potential of 6.6-30.2 mg TE/g of derived chitosans was relatively low, strong antimicrobial potential of chitosan was noted against Bacillus cereus and Listeria monocytogenes. The obtained results show that mushroom derived chitin and chitosan have a wide application potential and represent a viable path towards achieving a circular bio-economy.