Al30Zr and Al30Ti alloys are prepared by mechanical ball milling and hydrogenation, and their hydrolysis behavior is studied. The results show that alloying can regulate the microstructure and weaken the passivation film. Hydrogenation treatment further significantly improves the hydrogen production rate and hydrogen production, among which the promotion of reaction kinetics is more obvious. Under the condition of 353 K, the hydrogen production of Al30Zr increased from 1130 mL·g−1 to 1270 mL·g−1, and the hydrogen production rate increased from 11.33 mL·g−1·s−1 to 14.67 mL·g−1·s−1; the hydrogen production of Al30Ti increased from 1210 mL·g−1 to 1310 mL·g−1, and the hydrogen production rate increased from 12 mL·g−1·s−1 to 15 mL·g−1·s−1. Microstructural analysis shows that the metal hydride generated during the hydrogenation process is accompanied by volume changes, inducing particle cracking and refinement and introducing defects, thus changing the reaction interface state. In the process of hydrolysis, these structural changes promote the coordination of the reaction from a single interface to multiple positions, which is conducive to the continuous update of the interface. In contrast, Al30Ti shows better hydrolysis performance under medium and high temperature conditions, and the advantage is further enhanced after hydrogenation. The results show that the combination of alloying and hydrogenation can effectively regulate the structure and interface, thus improving the performance of hydrolysis and hydrogen production.
To investigate how tensile strain and strain rates affect the performance of bipolar plates (BPs) in proton exchange membrane fuel cells (PEMFCs), the microstructural evolution and corrosion behavior of laser metal deposited GH3536 alloy were examined using electron backscatter diffraction (EBSD), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), potentiodynamic/potentiostatic polarization tests, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Results demonstrate that the corrosion resistance of GH3536 alloy can be significantly improved with increasing strain and strain rate, reaching an optimum at 30% strain and 30 mm/min. This enhancement is primarily attributed to deformation-induced microstructural evolution, involving a high density of low-angle grain boundaries (LAGBs), an increased fraction of low-Σ coincidence site lattice (CSL) grain boundaries, high dislocation densities, deformation twins, and grain refinement. Furthermore, elevated strain rates not only facilitate the generation of extra LAGBs but also suppress their subsequent conversion to high-angle grain boundaries (HAGBs), creating a high density of preferential nucleation sites for the formation of low-defect passive films.
Based on relevant domestic and international literature and laboratory sample data, this study developed machine learning (ML) models for predicting the high-temperature deformation flow stress of all titanium alloys. The employed ML models include BP-ANN, SVR, and RF. The correlation coefficient (R), root mean square error (RMSE), and average absolute relative error (AARE) were used to evaluate the model performance. The test results indicated that the correlation coefficients of all three models exceeded 0.98. The selected composition parameters were verified as important parameters through sensitivity analysis (SA). In the flow stress prediction for different types of alloys, this study took experimental measurements as the benchmark and compared the prediction performance of the ML models, constitutive models, and the BP-ANN model based on a single-alloy system. The results showed that among near-β, α + β, and β-type alloys, the prediction performance of the three ML models was significantly higher than that of the Arrhenius model and close to that of the BP-ANN model for single-alloy systems. In the analysis of the influence of Al, Fe, V, and H contents on flow stress, the BP-ANN and SVR models exhibit high predictive performance. When investigating the influence of deformation process parameters (deformation temperature and strain rate) on flow stress, the RF model achieved a prediction accuracy of R = 0.9854 and AARE = 23.47
Hierarchical metal–organic framework (HS-MOF) films have attracted considerable attention due to their enhanced mass transport, larger accessible surface area, and superior performance in catalysis, separation, and sensing compared to conventional dense MOF films. However, the controlled fabrication of such hierarchical MOF films remains challenging. In this work, we present a facile and effective modulator-assisted strategy for the direct fabrication of hierarchical ZIF-8 films on bare Al substrates. By introducing stearic acid as a multifunctional modulator, we successfully orchestrate both the chemical environment and the growth kinetics during ZIF-8 crystallization. Stearic acid is proposed to play a dual role in ZIF-8 crystallization. It could serve as dynamic proton regulator, shifting the deprotonation equilibrium of 2-methylimidazole to control ligand availability and suppress homogeneous nucleation. Simultaneously, it serves as a competitive coordination ligand, forming transient zinc stearate complexes, which can buffer the release of zinc ions and guide the growth of hierarchical structures. This coordinated regulatory mechanism is suggested to not only inhibit the homogeneous crystallization process but also promote the directional heterogeneous growth of the substrate, thereby forming ZIF-8 films with tunable nanopore to micropore scales. Furthermore, the proposed strategy is also applicable to Zn substrate, providing a potential route for designing advanced MOF-based functional coatings.
Lattice distortion realized by entropy engineering can significantly optimize thermoelectric performance through intensifying phonon scattering. However, excessive lattice distortion in high-entropy materials inevitably hinders carrier transport, thereby limiting the wide-temperature average ZT (ZTave) value. To enhance the wide-temperature thermoelectric performance of low-cost PbS-based compounds, this work introduces moderate lattice distortion by controlling the entropy around 1.0R (R is the gas constant) to balance phonon and carrier transport, alleviating restrictions on carrier mobility. Firstly, substantial Se and Te alloying in PbS induces rock-salt lattice distortion, which effectively impedes phonon propagation, thus suppressing the lattice thermal conductivity (κlat) from 2.41 W m−1 K−1 in PbS to 0.66 W m−1 K−1 in PbS0.5Se0.35Te0.15 at 300 K. Additionally, Cu interstitials are introduced into the lattice-distorted PbS0.5Se0.35Te0.15 to further optimize the carrier density and weighted carrier mobility (μW), leading to a significant improvement in μW/κlat parameter at 300–773 K. Finally, a room-temperature ZT of 0.53 and a maximum ZT of 1.44 are obtained in a PbS0.5Se0.35Te0.15-1
