Journal of Materials Engineering and Performance最新文献

To enhance the corrosion resistance of soil contact machinery, FeCoNiCrMo HEA coatings were prepared on the surface of 65Mn steel using laser cladding technology, and nitriding treatment was carried out on this basis. The microstructure, phase composition, and hardness attributes of these coatings were meticulously examined through SEM, XRD, and nanoindentation methods. Findings indicate that following plasma nitriding, N has diffused into the material’s interior, with the diffusion depth and nitrogen content within the HEA coating exceeding those observed in the 65Mn steel. After the nitriding process of 65Mn steel, the surface predominantly comprises FeN_4. The coating of HEA predominantly comprises the FCC phase and the σ-Cr-Mo phase, supplemented by the presence of carbides. Compared with the HEA coating, the HEA composite nitriding coating forms FeN₄ and inhibits the formation of the FCC phase. Nitriding can increase the modulus of elasticity and nano-hardness of the materials, among which the HEA-coated composite nitrided samples showed the largest modulus of elasticity and nano-hardness of 206.37 and 16.49 GPa, respectively, which were 50.45 and 46.5% higher than that of the substrate, respectively. Kinetic potential polarization, EIS test, and immersion experiment were carried out in 0.5 M H₂SO₄ solution. The results show that both the HEA coating and the HEA composite nitriding coating have good corrosion resistance, among which the HEA coating has the best corrosion resistance. The self-corrosion current densities of both are relatively low, which are 0.00025 and 0.0015, respectively. The results of the immersion test show that there are large corrosion pits on the corroded surface of the substrate, while the corroded surfaces of the HEA coating and the HEA composite nitriding coating are relatively smooth.

The corrosion and pitting behavior of 2A14 aluminum alloy exposed to the marine atmosphere for six months were investigated. This study provides novel insights into the corrosion mechanisms of 2A14 aluminum alloy under marine atmospheric conditions, which are critical for improving its corrosion resistance in such harsh environments. The results indicated that severe pitting corrosion occurred on the surface of the 2A14 aluminum alloy, with pitting corrosion being identified as the primary form of corrosion. According to XPS analysis, the main corrosion products on the sample surfaces after six months of exposure at three different marine sites were Al₂O₃, Al(OH)₃, and AlCl₃. Notably, the corrosion degree of samples exposed closer to the coast was significantly greater, highlighting the influence of proximity to the sea on corrosion severity. The charge transfer resistance of the material decreased with increasing exposure time, suggesting a progressive degradation of the material's surface resistance to corrosion. Importantly, the corrosion products formed on the alloy surface exhibited stronger protective properties than the natural oxide film, although their protectiveness initially increased and then decreased as the corrosion process continued. This finding is novel and has significant implications for understanding the complex interplay between corrosion products and the underlying alloy surface. The results of this study will help guide the design, fabrication, and evaluation of 2A14 aluminum alloy, especially for applications in marine environments, by providing a deeper understanding of its corrosion behavior and potential strategies for enhancing its durability.

In this paper, 5083 Al/AZ31B Mg composite plates with added Ni foil were prepared by hot rolling, and the effects of Ni foil thickness (0, 5, 10, 25, and 50 μm) on the interface microstructure and the mechanical properties of the Al/Mg composite plates were investigated. The results show that the Ni foil added at the interface is fractured due to inhomogeneous deformation, showing a discontinuous band-like distribution at the interface. The presence of the Ni foil hinders the single interdiffusion between Al and Mg. Instead, a mixed interface composed of Al, Mg, and Ni forms, which is conducive to improving the interfacial bonding strength. Furthermore, the addition of the Ni foil interlayer contributes to the dynamic recrystallization of Al and Mg substrates near the interface, refining the grains at the interface, changing the grain orientation on the Al side and having a certain strengthening effect. As the thickness of the implanted Ni foil increases, the bonding strength and the tensile strength of the composite plate first increase and then decrease, and the largest values were obtained when the thickness is 25 μm, which are 5.9 N/mm and 245.25 MPa.

The paper investigates the effects of selective laser melting (SLM) processing parameters on the formability, microstructure, and mechanical properties of Al-Cu-Mg alloys with simultaneous additions of Sc and Zr. It systematically explores the relationship between laser volumetric energy density (VED) and macro-defects, as well as the mechanisms underlying their formation. The microstructure of the alloy is composed of equiaxed grains and columnar grains. An increase in energy density leads to the transformation of columnar grains into equiaxed grains. The alloy exhibits only a large number of primary θ (Al₂Cu) phase, which appears as continuous agglomerates. Additionally, an ellipsoidal w (AlCuSc) phase is observed within the θ (Al₂Cu) phase. The contributions of different strengthening mechanisms to the yield strength of the alloy are obtained through theoretical calculations.

This study investigates the enhancement of corrosion resistance in Zn-Al coatings by the application of novel ZIF-8 hydrophobic films, synthesized using a secondary growth method with varying molar ratios. The effectiveness of ZIF-8 films was assessed through electrochemical corrosion tests, scanning electron microscopy, atomic force microscopy, and electron probe microanalysis. Results indicate that ZIF-8 films prepared by the secondary growth method exhibit greater density and smoothness compared to those produced by traditional methods. The ZIF-8 hydrophobic films significantly improved the corrosion resistance of Zn-Al coating, with the ZIF-8 film at a molar ratio of 1:16 demonstrating the best corrosion protection performance. After 2 h of corrosion, ZIF-8 films with a molar ratio of 1:16 demonstrated the highest corrosion resistance, achieving a charge transfer resistance (R_ct) of 13218 Ω/cm², which is two orders of magnitude higher than that of uncoated Zn-Al coating. ZIF-8 films exhibited significant corrosion protection potential on Zn-Al coatings, providing important theoretical and experimental support for the development of high-performance corrosion-resistant coating. This has broad application prospects, particularly in corrosion protection for metal structures in bridges and transportation infrastructure, such as the main cables of offshore bridges and cross-sea bridges.

The lithium-ion battery cells in electric vehicles are created in part by welding many layers of electrode foils to a tab to create the cell lead. While this process has conventionally involved an ultrasonic welding process, there is a desire to replace this process with laser welding to address certain limitations and remove a process step. The literature surrounding laser welding of multilayer thin foils to tabs is limited. This research aims to address this gap by developing a process window for green laser welding of multilayer foil-to-tab copper welds. Multiple copper foil layers, from 30 layers to 90 layers, were joined to a copper tab using a green laser with varying power and speed. The welds were analyzed based on micrographs, x-ray, failure load, and fracture mode. Process windows were developed for the various stack-ups. It was observed that very low heat input results in a narrow weld width and hence interfacial fracture under lap-shear loading. With suitable power and speed parameters, a process window exists where the welds have a minimum interface width greater than 180 µm, leading to fracture at the foil-weld fusion boundary. It was observed that excessive weld energy results in a weld with high porosity. Foil cut-through associated with excessive surface variation occurred under high speed and high-power conditions. As the number of foil layers increased, the process window is reduced due to the increasing number of defects present.

In the present work, 12% tin bronze (CuSn12) was subjected to solutioning, artificial aging, and cryogenic treatment. The as-received CuSn12 material contained the α-solid solution and the δ-eutectoid (a mixture of the α- and δ-phases). Solutioning induced complete dissolution of the δ-phase. Subsequent artificial aging evoked discontinuous precipitation of the ε-phase at the grain boundaries. Cryogenic treatment accelerated discontinuous precipitation. Moreover, these treatments resulted in a substantial increase in the number of fine deformation twins inside the α-solid solution grains, which may act as preferential sites of continuous precipitation. Because grain boundary diffusion is much faster than grain interior diffusion, precipitation at the grain boundaries was much more pronounced. Consistently, microhardness increased substantially in the nearby grain boundary regions. All treatments reduced hardness and the yield strength but increased ductility and impact toughness. Aging had a slight but indisputable effect on all mechanical properties (an increase in hardness and yield strength but a decrease in ductility and toughness).

Adding refiners to the melts is one of the most efficient refining methods for magnesium alloys. How to improve the effectiveness of refiners was a significant issue in the Mg alloy foundry industry. Commonly used methods (e.g., electromagnetic and ultrasonic techniques) required sophisticated equipment and involve high costs. In this study, the improvement in refining effect of Al-NbB₂ refiner on AZ91 alloy was realized by the addition of Gd elements. The Al-NbB₂-xGd (x = 0, 0.3, 0.5, 0.7) refiners for AZ91 alloy were prepared by solid-liquid reaction method. Adding 0.5 wt.% Gd to the Al-NbB₂ refiner reduced NbB₂ particle size, altered its morphology (hexagonal prism → spherical polyhedron), and improved its distribution and dispersion, significantly enhancing refining performance. The Al-NbB₂ refiner showed better refining effects than other commonly used refiners. Compared with the refining effect of Al-NbB₂ refiner on AZ91, the grain refining effect of Al-NbB₂-0.5Gd refiner on AZ91 alloy was enhanced by 30% (78–55 μm). The yield strength, tensile strength and elongation were increased by 8% (74–80 MPa), 12% (151–169 MPa) and 12% (5.1–5.7%), respectively. The existences of NbB₂ and Al₃Gd particles in AZ91 alloy was demonstrated using high-resolution transmission electron microscopy (HRTEM). The matching relationships between particles and α-Mg were determined using the edge-to-edge model (E2EM). The refinement mechanism of refiners in AZ91 alloy was analyzed.