Abstract This study examined the influence of porosity on the mechanical behaviour and wear performance of Ti-18Nb-9Cualloys (wt. %) fabricated via powder metallurgy using ammonium bicarbonate as a space holder at varying volume fractions (30%, 40%, 50%, and 60%). Compression tests showed that increasing porosity led to significant mechanical degradation: the elastic modulus decreased by approximately 80%, and the ultimate compressive strength dropped by 74% as porosity increased from 29.7% (30 vol.% space holder) to 48.1% (60 vol.% space holder). Tribological evaluations under dry sliding conditions revealed that the specific wear rate increased nearly eightfold. Surface roughness (Ra) values rose from 0.969 µm to 1.982 µm, indicating increased topographical irregularity. These results underscore the critical influence of controlled porosity on the mechanical integrity and wear resistance of Ti-18Nb-9Cu alloys, highlighting their potential for load-bearing biomedical implant applications.

Abstract The present investigation explores the microstructural stability, mechanical properties and strengthening mechanisms of spark plasma sintered (SPS) nano/ultrafine grained AlCuZr, AlCuNb, and AlCuY alloys for lightweight structural applications. The SPS was carried out at 350, 450, and 550 °C on cryo-ball milled Al4.5%Cu, Al4.5%Cu1%Zr, Al4.5%Cu1%Nb, and Al4.5%Cu1%Y alloys. When SPS was carried out at 550 °C, the highest densification was found to be 97%, 97%, and 98%, respectively, for all the samples. This is due to exceptional diffusion bonding between the particles. The corresponding average grain size measured in nanometers (i.e., less than 100 nm) was confirmed by TEM microstructural analysis. Similarly, the yield strength (YS) was measured to be 620, 615 and 600 MPa, respectively, for the Al4CuZr, AlCuNb, and AlCuY alloys, which are significantly superior to those alloys SPSed at 350 and 450 °C. An improved mechanical property at 550 °C is due to the insoluble stabiliser (i.e., Zr, Nb and Y), which acts as an obstacle to the movement of grain boundaries and accumulation of more dislocations (strain hardening). Furthermore, the strengthening mechanisms were also quantified by considering experimental data (i.e., alloying, TEM, and XRD) and comparing with test data (YS). Grain size reduction is observed to be a significant strengthening mechanism for the YS as contrasted to the other mechanisms.

Abstract The unavailability of embedded-atom method (EAM) potential for the Platinum–Barium (Pt–Ba) alloy system, which is an enticing choice as cathodes for magnetron amplifiers due to their high electron emission coefficient and excellent work function. The parameterization of an EAM potential for this alloy system has been described in part 1 portion. Studying different deformation mechanisms is crucial for these kinds of alloy systems in order to implement them in critical engineering applications. Tensile and creep characteristics have already been reported in part 1, along with the validation of density, cohesive energy, and elastic properties. Here, a list of other fundamental properties, such as lattice constant, surface energy, and lattice thermal conductivity, have been investigated via molecular dynamics (MD) simulation and compared with density-functional theory (DFT) analysis to concretize the accuracy of the potential. Thereafter, MD simulation has been used to study the deformation behavior of single crystal BaPt2 compound under asymmetric cyclic loading having “R” (stress ratio) of −0.2, −0.4, and −0.6 at different temperatures ranging from 300 K to 1600 K using the parameterized EAM potential. A constant strain rate of 108/s has been used in this present study. Although variations in strain axis are not significant, an increase in ratcheting strain with the increment in temperature and an increase in strain accumulation with the decrease in magnitude of stress ratio have been observed. Strain amplitude decreases and stabilizes at a terminal value, as observed from the strain cycle plot.

Abstract TiO2 nanocomposites doped with Zn have been prepared via the sol-gel method. These nanocomposites with various doping percentages exhibited multi-phase structures with promising photocatalytic efficiency for the removal of pollutants, manifested by methylene blue degradation. Common characterization techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and UV–Vis spectroscopy, were employed to characterize the prepared samples. The identified phases are the rutile tetragonal and wurtzite hexagonal crystal structures of TiO2 and ZnO, respectively, while the doped samples tend to exhibit multi-phase structures of rutile, anatase, zincite, spinal, and inverse spinel cubic phases. Doping significantly influenced the energy gaps, which ranged from 2.9 eV to 3.45 eV. SEM morphological studies confirmed that the average size of the nanoparticles was around 150 nm, while the size of the crystallites varied with doping, ranging from 18 nm to a maximum of approximately 42 nm at a 5 wt% of Zn doping, which is manifested as the optimal doping amount that enhanced the properties of the nanocomposite. However, further increases in doping concentration resulted in the creation of additional scattering centers, which negatively impacted photocatalytic efficiency. The optimal doping ratio resulted in a photocatalytic efficiency of about 98%.

Abstract The present study investigated the various aspects of mechanical behaviour, microstructure evolution, and formability of a SS430/AA1050 clad sheet at three different elevated temperatures with or without lubrication. Tensile experiments revealed a reduction in tensile strength and ductility of the SS430 layer at elevated temperatures, while the AA1050 layer showed a decrease in strength but an increase in its ductility when compared to that of at room temperature. The average normal anisotropy was also increased for both layers of the sheet, enhancing overall clad sheet formability. At elevated temperatures, recovery and recrystallization influenced texture intensity significantly, especially in AA1050, resulting in a more random distribution of grain orientation, however, the texture of SS430 become stronger after deformation. With MoS2 as lubrication, friction values decreased notably for both the layers, reducing sticking friction during forming operations. Forming limit diagrams demonstrated improved limit strains under lubrication, with major strain at plane strain condition increasing more than 65% at 300°C compared to the dry conditions. Deep drawing experiments of the clad sheet revealed that the lubricant significantly improved drawability at all temperatures. Also, the use of lubrication increased the limiting draw ratio, with a maximum draw ratio of 2.0 achieved at 300°C. An analytical model was also developed to predict the required punch force in the deep drawing of the clad sheet based on the Barlat-89 anisotropic yield criterion. The results achieved by numerically and analytically were observed to be in a good agreement with the experimental results.

Abstract Welding dissimilar metals such as Inconel 625 and 316L stainless steel presents significant challenges due to differences in their thermal conductivity, melting points and mechanical behavior, often leading to defects like cracks, porosity and incomplete fusion. These are particularly critical in demanding environments such as underwater, aerospace and nuclear applications, where joint integrity and reliability are essential. To address these challenges, this study investigates the feasibility and optimization of Ultrasonic Vibration Assisted Laser Welding (USALW) for joining Inconel 625 and 316 L stainless steel. A Box-Behnken design under Response Surface methodology (RSM) was used to conduct experiments and analyze the effects of input parameters such as laser power, ultrasonic power, shielding gas flow rate, and weld bead clearance and on output responses such as tensile strength, weld penetration, impact toughness and corrosion resistance. To enhance prediction accuracy and parameter optimization, a hybrid Interpretable Artificial Intelligence (IAI) framework was developed, combining a Recurrent Neural Network (RNN) for predictive modeling, Local Interpretable Model Agnostic explanations (LIME) for interpretability and Moth Flame Optimization (MFO) for solution optimization. The proposed IAI model achieved high accuracy (R2 > 0.99) and effectively identified the most influential process parameters. The optimized welds demonstrated significant improvements in mechanical and corrosion properties. This integrated approach not only improves weld quality but also provides transparency and reliability in the predictive modeling of complex welding processes.

Abstract Welding procedures in high-hardenability steels often lead to adverse microstructural changes, resulting in a sharp decline in mechanical properties within the weld metal zone and the heat-affected zone. Due to the limited tensile strength Rm of commercially available welding consumables, which in many cases do not exceed 1000 MPa, the reduction in mechanical properties can reach up to 60% in steels with hardness levels of 600 HBW. Martensitic boron steels are among the materials with the highest mechanical strength indices and are used both in components exposed to abrasive wear and in ballistic protection. Consequently, welding techniques often produce joint zones with functional properties (e.g., ballistic resistance or resistance to abrasive wear) that fail to meet the required performance of the base material. Only through advanced welding techniques, the use of high-quality fillers, and subsequent heat treatment can the highest mechanical strength indices be achieved in the weld zone. This article presents the results of tests on the resistance of 450 HBW grade steel welded joints to dynamic loads. The research demonstrated that, when subjected to firing using intermediate 7.62 × 39 mm ammunition (43 model, PS bullet) from a distance of 10 m, a minimum plate thickness of 5 mm ensures material continuity across all characteristic zones of the welded joint.

Abstract Bidirectional silica fabric-based polymer composite laminates were fabricated using resin transfer molding followed by oven curing. To evaluate the effects of environmental exposure, samples were cut as per testing requirements, and a substrate was surface-coated with a 300-µm-thick polyurethane (PU) layer. Both PU-coated and uncoated samples were subjected to hot-wet conditioning in a climatic chamber for 100 days under critical conditions of 65 °C and 85% relative humidity (RH). In this study, density, thermal conductivity, pull-off adhesion, scratch resistance, and various mechanical strengths at room temperature and 100 °C were measured before and after conditioning. For uncoated composites, a significant effect of hot-wet conditioning on mechanical strengths, with reductions ranging between 15 and 30%, was observed. When compared between uncoated and coated composites, coated composites exhibited an additional reduction in tensile strength, flexural strength by 14–25%, and interlaminar shear strength decreased from 53 MPa (uncoated, after conditioning) to 46 MPa (after coating & conditioning), although compression and in-plane shear strengths were relatively unaffected. Furthermore, coated samples experienced over a 35% reduction in scratch resistance and pull-off adhesion strength (declined significantly from 8.1 MPa to 5.1 MPa), while density and thermal conductivity remained unchanged. These degradations were attributed to the formation of micro-crevices between the composite substrate and the PU coating, resulting in cavitation damage and matrix degradation. Based on these findings, PU coatings are not recommended for outdoor applications wherein environmental conditions are 65 °C and 85% RH.

Abstract This study examines the corrosion resistance of H13 tool steel exposed to ionic molten salt solution through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. H13 steel samples were produced via selective laser melting (SLM) with three different build orientations (0 deg, 45 deg, and 90 deg) using the Build Processor v3.2 machine. Nyquist and Bode plots, along with polarization curves, were used to assess the impact of orientation on corrosion resistance. The findings were supported by microstructure analysis of the corroded samples using optical and scanning electron microscopies. The phase angle and the impedance modulus increased with building orientation, with the 0 deg orientation showing the highest values. Polarization resistance values were 1704 Ω cm2, 1540 Ω cm2, and 1430 Ω cm2 for 0 deg, 45 deg, and 90 deg, respectively, demonstrating superior corrosion resistance for the 0 deg orientation. Results highlight the critical impact of SLM build orientation on corrosion resistance, providing insights for future corrosion mitigation strategies for alloys.

Abstract The mechanical properties and microstructure of different diffusion bonded trials of 316H Stainless Steel were compared to analyze the correlation between mechanical properties and the microstructure of the bonded material. The results show that the percent coverage of grain growth across the bond interface can be correlated to the ductility and the ultimate tensile strength of the bonded material. This correlation could be used to help identify whether or not a bond is of good quality. Additionally, the effects of bonding temperature and time can be seen on the quality of diffusion bonded 316H Stainless Steel. With an increase in temperature and time, the percent coverage of the bond line increased as well as the ductility of the material. When prioritizing ductility at high temperatures, bonding conditions of 1150°C for one hour at an 8 MPa interface pressure with a three-hour annealing time under vacuum provided the best results.