The thermal effects of TC4 titanium alloy during laser welding induce microstructural heterogeneity and residual stress in the weld joint, significantly compromising its corrosion resistance. This study investigated the influence of pulsed magnetic field treatment with varying intensities (0.5, 1, 1.5, and 2 T) on the corrosion behavior of welded joints. Results show that magnetic field treatment effectively enhances corrosion resistance, with optimal performance achieved at 1.5 T. Compared to untreated specimen, the 1.5 T-treated specimen exhibits remarkable improvements: polarization resistance (R-p) increases by 13 times, corrosion current density (I-corr) decreases by 30.3%, passivation current density (I-p) reduces by 40.5%, while mass loss rates after HCl immersion for 20 and 40 d decrease by 1.7% and 10.3%, respectively. The decrease in homogeneity index (D-value) of residual stress distribution show a trend of initial increase followed by decrease with ascending magnetic intensity. At 1.5 T, the D-value reduction in x-direction reaches 27.92%, corresponding to optimal energy matching between magnetostrictive effects and dislocation motion. Beyond 1.5 T, magnetostriction saturation induces lattice distortion and dislocation pile-ups, diminishing stress redistribution efficiency. Magnetic treatment facilitates dislocation migration and annihilation, reducing local strain (5.8% -6.9% decrease in KAM(ave)) and residual tensile stress (72.0% reduction). This process alleviates stress concentration and decreases the proportion of low-angle grain boundary, effectively releasing type II internal stresses and decreasing corrosion susceptibility. This research proposes an innovative, costeffective, and eco-friendly post-processing strategy for titanium alloy welded structures.
High-entropy alloys (HEAs) are emerging alloy materials in recent years, breaking the inherent concept of designing traditional alloy compositions based on 1-2 major elements. Due to their unique structural features and performance advantages conferred by their multi-principal-element combinations, HEAs exhibit wide application prospects in marine engineering. In this review, the basic concepts and development status of HEAs have been introduced. Furthermore, their technological breakthrough, performance features, and corresponding mechanism analysis in different scenarios, including structural mechanics, coating protection, corrosion resistance, radiation tolerance, and component fabrication, have been reviewed. Special attention has been paid to the development status and application scenarios of HEAs in the field of shipbuilding and marine engineering. Some prominent problems currently existing in the research process of HEAs have been summarized, aiming to propose design methods and preparation directions of HEAs. More importantly, it also clarified novel development strategies to solve practical problems such as a series of corrosion and protection issues faced by HEAs under complex service conditions including marine engineering, along with new ideas for the future development of advanced HEAs that possess superior comprehensive performance and enhanced environmental adaptability.
The elastic modulus of metallic glasses (MGs) is commonly considered to be "inherited" from their solvent (principal) element. However, this rule exhibits significant exceptions in Cu-based MG systems. To uncover the physical mechanism behind this anomalous inheritance, this study selected the Cu-Zr-Hf-Ti system as the research object. Based on first-principles calculations, a multi-scale analysis was conducted, including the macroscopic elastic modulus, atomic-scale bonding characteristics, and the electronic structure. The results show that the elastic modulus of this system is governed by low-stiffness interatomic interactions represented by Zr-Zr and Zr-Ti bonds, rather than by the principal element Cu. Electronic structure analysis further confirms that, although Cu dominates in composition, the electronic density of states (DOS) near the Fermi level is primarily contributed by the d-orbitals of the minor elements Zr and Hf. The introduction of Hf enhances the orbital hybridization between Cu-3d and Hf-5d, and reduces DOS near the Fermi level, thereby significantly increasing stiffness by promoting the directionality and covalency of bonding. Concurrently, the decrease in ratio of bulk modulus to shear modulus (B/G) and Poisson's ratio (n) values suggests a potential decline in toughness. This work clarifies that the inheritance of the elastic modulus in MGs is essentially determined by the key element that dominates the electronic DOS at the Fermi level. This finding provides a theoretical basis for the rational design of MGs with tailored mechanical properties from an electronic structure perspective.
High-performance noble metal electrocatalysts for water splitting face significant challenges including high cost, low atomic utilization, insufficient interface stability, and complex preparation processes, which severely limit their large-scale application. Therefore, developing lowcost, low-energy-consumption, and long-life electrocatalysts for water splitting is urgently needed. In this work, a carbon thermal shock strategy was used to rapidly synthesize ultrafine (10 nm) FeCoNiCrPt high-entropy alloy (HEA) nanoparticles on carbon fibers. Results show that in alkaline medium, the catalyst achieves current densities of 10 mA & centerdot;cm(-2) for the hydrogen evolution reaction (HER) and 100 mA & centerdot;cm(-2) for the oxygen evolution reaction (OER) with overpotential of only 34 and 264 mV, respectively. Furthermore, when FeCoNiCrPt samples are used as both anode and cathode in an alkaline electrolyzer for overall water splitting, a current density of 10 mA & centerdot;cm(-2) is achieved at only 1.53 V, with stable operation for more than 100 h. This carbon thermal shock strategy provides a simple and versatile approach for rapidly synthesizing well-dispersed HEA nanoparticles, offering a new pathway for developing low-cost, highly stable catalysts for overall water splitting.
In-situ ceramic phase-reinforced TaMoTiCr refractory high-entropy alloy (RHEA) composites were prepared by spark plasma sintering with the addition of 2.5wt% and 5.0wt% h-BN, separately. Results show that the h-BN promotes the uniform formation of (Ti, Ta)N, TaB2, and MoB ceramic phases within the body-centered cubic matrix, significantly increasing microhardness to 1136.95 HV. Tribological test results show that the composite with the addition of 2.5wt% h-BN presents great performance at room temperature with an ultra-low wear rate of 1.64 & times;10-7 mm3 N-1 m-1, while the composite with the addition of 5.0wt% h-BN shows optimal performance at 300 degrees C. Above 800 degrees C (elevated temperature condition), lubricious oxide tribolayers, rich in Cr2O3, TiO2, and B2O3, form on the material surface, effectively reducing friction and wear. At 1000 degrees C, the composite with the addition of 2.5wt% h-BN achieves a wear rate of 5.22 & times;10-7 mm3 N-1 m-1. This in situ ceramic reinforcement approach effectively enhances wear resistance of RHEAs across a wide temperature range, offering great potential for advanced aerospace applications.
