The feasibility of spinel-type high-entropy oxides (HEOs) has been confirmed as electrode materials for supercapacitors. However, HEOs still have significant drawbacks in terms of cycling stability and electrical conductivity. Carbon nanotubes (CNTs) are ideal candidates for HEO composite modification with high strength and conductivity. HEO/CNT composites were firstly synthesized with different component ratios using a one-step hydrothermal method. The results indicate that when the A-site metal compounds for preparing the high-entropy oxide are each 1.1 mmol, the addition of 40 mg of CNT yields the optimal composite effect. Under a current density of 1 A g-1, the specific capacitance of HEO/CNT-40 in a three-electrode system could reach 1622 F g-1. When the material was integrated with activated carbon to form a supercapacitor, the device achieves an energy density of 22.08 Wh kg-1 and a power density of 941.8 W kg-1. After 10000 charge-discharge cycles at a current density of 10 A g-1, the device exhibits a capacity retention rate of 87% and a coulombic efficiency of 100%. This provides a reference and inspiration for exploring the application of high-entropy oxides in supercapacitors.

Friction stir deposition of Al-Zn-Mg-Cu alloys often suffers from abnormal grain growth (AGG) during subsequent solution treatment, negating the fine-grain advantage and impairing toughness. This study addresses this challenge by introducing 1.5 wt% Mn into an Al-10Zn-2Mg-1Cu alloy. The added Mn led to the formation of thermally stable Al6Mn phase, which effectively pinned grain boundary during a 470 degrees C/1h solution treatment, successfully inhibiting AGG and maintaining a fine-grained microstructure (similar to 1.8 mu m). Following a 150 degrees C/4h peak-ageing treatment, a high density of nanoscale eta ' precipitate (similar to 15 nm diameter, similar to 4 nm thickness) formed, providing substantial precipitation strengthening. Consequently, the friction stir deposited Al-Zn-Mg-Cu-Mn alloy achieved a high ultimate tensile strength of 625 MPa with an elongation of 10.2%. This strength surpasses most reported friction stir deposited precipitation-strengthened aluminum alloys and is comparable to morph + heat-treated AA7085. The strategy of utilizing stable Al6Mn phase to suppress AGG enables the retention of a fine-grained, high-strength, and ductile microstructure in friction stir deposited ultra-high-strength aluminum alloys, enhancing their potential for large aerospace components.

This study investigates the role of austenite domain size in governing the electrochemical corrosion behavior of UNS S32205 duplex stainless steel. Specimens with a quantified range of austenite domain sizes were subjected to electrochemical testing in 0.1 - 1.0 M NaCl solutions, complemented by analyses of post-corrosion morphology and surface composition. The results demonstrate that microstructures with finer austenite domains exhibit systematically superior corrosion resistance across all tested conditions. This is evidenced by a higher charge transfer resistance, a lower corrosion current density, and a more stable passive film compared to their coarse-structured counterparts. The enhancement is attributed to accelerated repassivation kinetics and the geometric confinement of corrosive attack within the refined dual-phase network, which effectively suppresses stable pit growth within the less-connected ferrite phase. This work establishes austenite domain size as a master microstructural variable for controlling localized corrosion in 2205 DSS, providing a scientific basis for optimizing the alloy's durability through microstructural refinement strategies during thermo-mechanical processing.

In this study, Cu-Cr-Zr alloys with trapezoidal and rectangular cross-sections were cold-forged and subsequently aged, ultimately enhancing mechanical properties without compromising electrical conductivity. Compared with conventional rectangular cross-sections, the trapezoidal design promotes refined grain boundary precipitates (0.67 mu m vs. 1.52 mu m) and near-coherent Cr2Zr dispersoids within the alpha-Cu matrix, simultaneously maintaining precipitate size uniformity. These microstructural features collectively contribute to superior yield strength (318.7 MPa), tensile strength (692.9 MPa), and elongation (19.6%) as well as a high conductivity (81% IACS). Fractographic and work hardening analyses reveal that the trapezoidal specimen's performance stems from its homogeneous precipitate distribution and stable strain hardening behavior, both consequences of the geometrically induced stress field during forging. The findings establish cross-section design as a critical processing parameter for achieving synergistic strength-ductility-conductivity in precipitation-hardened copper alloys.

Layered double hydroxide (LDH) is a material with unique advantages, including high redox properties, tunable composition and microstructure, and could be prepared by simple synthesis processes. In this study, we introduce a novel design pathway that leverages these properties to achieve both wastewater treatment and energy storage using LDH materials and their derivatives. We synthesized a sodium dodecyl sulfate (SDS) anion intercalated NiCo-LDH using a straightforward hydrothermal method, which increased the interlayer distance and enhanced Cr(VI) adsorption. The unit adsorption of chromium ion was an impressive 78.8 mg g-1 at an adsorbent dosage of 1 g L-1. Subsequently, the LDH after adsorption was heat-treated to stabilize the adsorbed chromium in the adsorbent, resulting in a Cr-doped sample (Cr-NiCo2O4). The electrode derived from this process exhibites a high mass-specific capacitance (328.3 F g-1 at 1 A g-1), surpassing NiCo2O4 (273 F g-1). Assembled into an asymmetric supercapacitor (ASC), it demonstrated a specific capacitance of 70.2 F g-1 at 1 A g-1 and excellent cycling stability (88.23% retention after 10,000 cycles). This innovative design pathway not only meets the Cr(VI) adsorption requirement but also produces high-performance supercapacitor electrode materials, offering considerable practical utility and future application prospects.

Spinel oxides are promising supercapacitor electrode materials due to their abundant active sites and tunable composition, yet their low conductivity limits energy density. This study employs entropy engineering to design a high-entropy spinel oxide, (Co0.2Ni0.2Cr0.2Mn0.2Cu0.2)Fe2O4, by incorporating equiatomic metal dopants at the A site. Structural and chemical analyses confirm the successful synthesis of a single-phase high-entropy spinel. The material demonstrates exceptional electrochemical performance in 1 M KOH, achieving a specific capacitance of 1489 F g 1 at 1 A g-1, surpassing most reported high-entropy oxides. In an asymmetric supercapacitor with activated carbon (AC) as the negative electrode, it delivers a high energy density of 31.875 W h kg-1 at 1074.8 W kg-1. Remarkably, after 5000 cycles at 10 A g-1, the material retains similar to 60% of its initial capacitance with similar to 90% coulombic efficiency. This work highlights a viable strategy for developing high-entropy electrode materials with significant application potential.

A new type of nickel-based single-crystal superalloy was subjected to creep performance test, microstructure observation, and composition analysis under the condition of 1100 degrees C/140 MPa. The variation characteristics of the creep rate during the creep fracture process and the microstructure evolution before and after creep were investigated, thereby revealing the creep fracture mechanism of the new nickel-based single-crystal superalloy. The results indicate that the creep life of the alloy is 104.5 h, and the strain can reach 33.58%. The creep rate decreases first, then increases, and finally tends to be stable until fracture. At the initial stage of creep, the creep rate decreases first, then rises and finally decreases again with time. Furthermore, the creep fracture microstructure is composed of dimples and tearing edges without obvious slip planes. Oxides and recrystallized structures exist inside the fracture surface, and the voids inside the fracture are elongated and perpendicular to the stress axis, showing a fracture mechanism of microcrack accumulation.

Based on the excellent performance of novel high-entropy hydroxides, we investigate the relationship between pseudocapacitive performance and catalytic oxygen evolution in alkaline aqueous electrolyte systems.

This research presents a method to construct multilevel micronano structures by exploiting the highly tunable composition and morphology of NiFe-layered double hydroxides (NiFe-LDHs) and metal-organic frameworks (MOFs) and introducing sulfide ions (S2-) to improve composite conductivity. It effectively mitigates issues of poor cycle stability caused by the inherent volume expansion of transition metal sulfides (TMSs) and the agglomeration of electrode materials under high mass loading conditions, which significantly improves the electrochemical performance. Notably, at the current density of 1 mA cm-2, the C-Co9S8/NiFe-S@NF electrode demonstrates an exceptionally high capacitance at approximately 17,338.6 mF cm-2. As an asymmetric supercapacitor (ASC) electrode, C-Co9S8/NiFe-S@NF demonstrates energy and power densities of 1.05 mWh cm-2 and 51.75 mW cm-2, respectively. Moreover, the ASC device exhibits remarkable stability under cycling, with an 82.6% retention of its capacity and consistent Coulombic efficiency of 93.8% after 5000 cycles at a current density of 30 mA cm-2. This study demonstrates that the multilevel micronano structured self-supporting electrode not only enhances the charge storage capacity but also strengthens the overall electrochemical stability of the electrode considerably. The findings offer a promising pathway for developing energy storage devices with superior performance, leveraging the synergistic effects of the integrated MOFs/NiFe-LDHs composite structures.

The poor conductivity and severe agglomeration of layered double hydroxides (LDHs) limit their practical applications. To improve their crystallinity, hydrophilicity, and conductivity, this study proposes a novel synthesis method. Using zeolitic imidazolate framework (ZIF-67) as a template, LDH was combined with polypyrrole (PPy) and doped with aluminum ions to obtain a unique three-dimensional layered nanocage composite material named as PPy@NiCoAl0.1-LDH (PPy@NCA0.1-LDH). The larger pores and more active sites improve the electrochemical performance. The PPy@NCA0.1-LDH electrode shows a specific capacity of 1900 F g- 1 at a current density of 1 A g- 1 and maintains 84.1 % capacitance retention after 5000 cycles at 5 A g- 1. The asymmetric supercapacitor achieves an energy density of 35.35 Wh kg- 1 at a power density of 799.87 W kg- 1 and is stabilized at 18.2 Wh kg- 1 even at a power density of 5748 W kg- 1. These results indicate a significant improvement in the performance of supercapacitors, making them be more promising candidates for practical applications.

High-entropy MXenes (HE-MXenes) represent a highly promising frontier in 2D materials, but their safe, fluorine-free synthesis remains a critical challenge. Recently, Lewis acidic molten salt etching has been emerged as a promising alternative due to its high operational safety and precise regulation of MXene surface terminal groups. This work reports a strategy utilizing anhydrous CuCl2 to etch the high-entropy MAX (HE-MAX) phase, (TiVNbMoW)3AlC2. The investigation reveals that the reaction is hindered by the formation of a previously unreported amorphous intermediate structure (M3C2-ClCux). However, this intermediate phase, trapped at a specific etchant concentration, degrades the material's electrochemical performance. By optimizing the etchant ratio, the adverse influence of the M3C2-ClCux on the electrochemical performance is effectively mitigated, enabling the successful synthesis of an accordion-like HE-MXene. The electrochemical energy storage performance of this HE-MXene is systematically evaluated in acidic and alkaline electrolytes. More importantly, this study not only presents a viable F-free synthetic route for HE-MXene but also reveals a novel reaction mechanism that is crucial for future process optimization and rational material design.

2D transition metal carbides, nitrides, and carbonitrides (MXenes) are widely used in energy-related fields, however, the instability of MXenes limits their application in supercapacitors. Currently, one of the main scientific challenges is how to modify MXenes to enhance their electrochemical performance. Compared to mono-transition-metal MXenes (MTMs), the large surface combined with multiple transition metals makes high entropy MXenes (HE-MXenes) more appealing in energy storage. Here, a HE-MAX phase, (TiVNbMoW)3AlC2, and a corresponding accordion-like HE-MXene are successfully synthesized by selective removal of Al from the HE-MAX in aqueous hydrofluoric acid (HF). The addition of W allows the high-entropy MAX (HE-MAX) to reach greater lattice distortion than (TiVNbMo)3AlC2. It also successfully resolves the problem of inadequate configurational entropy in the M layer and expands the range of M layer. The accordion-like HE-MXene with open microstructure and high crystallinity provides multi-channels for rapid ionic charge diffusion during interlayer ion insertion/extraction. Owing to these designs, the capacity retention rate is 98.7% after 10 000 cycles at 5 A g-1, demonstrating high stability throughout the charge-discharge cycling both in acidic and alkaline. The synthesis of HE-MXene enriches the selection for energy applications and greatly increases the compositional variety of the MXene family.

Supercapacitors are electrochemical energy storage devices with great potential applications. Meanwhile, the oxygen evolution reaction (OER) determines the efficiency of some electrochemical energy conversions. This study aims at constructing, exploring, and optimizing Ramsdellite-MnO2@NiCoAl-LDH@CC (R-MNCA@CC) composites. The effect of microstructure and Al role on the performance is investigated when R-MNCA@CC was used as supercapacitor electrode material and OER catalyst. Coral-like R-MNCA@CC in-situ growth composites were synthesized by a two-step hydrothermal method. R-MNCA@CC-2 (molar ratio of Ni:Co:Al is 1:1:1) performs the best with the largest specific capacitance, 1,742 F/g at 1 A/g, increased by 797% and 1,489% compared to that of NiCoAl-LDH and Ramsdellite-MnO2. The capacitance retention rate of the R-MNCA@CC-2//AC@CC supercapacitor is 80.1% after 5,000 cycles at 0.8 A/g. The overpotential for driving an OER to reach 10 m/cm2 is only 276 mV, which is lower than that of commercial IrO2 (300 mV). Noteworthy, we propose a view that is “competing to trigger redox reaction” of electrochemical active sites in LDH during electrochemical processes derived from a discrepancy between theory and experimental results.

This paper reports the correlation between strengthening behaviors and strength differential effect of nano-ZrB2particle/AA6xxx alloy composites. The microstructures were characterized and mechanical properties of composites were investigated. This study examines the different strengthening behaviors under tension and compression. The changes of strain direction surrounding the nano-ZrB2 particles during the plastic deformation were analyzed with the aid of finite element analysis. The distribution of rotation angles of the strain directions indicates a different symmetric characteristic in compression and tension. The established relationship between strength differential effect and strengthening behaviors suggests that the asymmetry of strain surrounding the nano-ZrB2 particles during the deformation is responsible for the strength differential effect.

The elements of Sc and Zr have been used to modify the Al-Mg alloys to improve the Selective Laser Melting (SLM) processability and enhance the mechanical properties. However, these alloys are very expensive due to the addition of Sc. In this study, Er is used as a cost effective substitute for Sc in an Al-Mg alloy processed by SLM and the effects of Er in combination with Zr on microstructure and mechanical properties are investigated. It is found that with optimized laser parameters, Er and Zr result in excellent grain refining, forming a bimodal grain structure with fine equiaxed grains (-0.8 & mu;m) and columnar grains (2-10 & mu;m). The grain refinement is mainly attributed to the heterogeneous nucleation effect and the grain boundary pinning effect of the Al3Er and Al3(Er, Zr) particles. The as processed condition shows a large amount of Al3Er and Al3(Er, Zr) precipitates 5-50 nm in size with L12 structure, and additional post-SLM aging treatment is not required as it does not provide further benefit in hardness. The Al-Mg-Er-Zr alloy exhibits a room temperature tensile strength of 340 MPa and 329 MPa in x and z directions respectively, as well as a 300 degrees C tensile strength of 107 MPa and 102 MPa in x and z directions, making this alloy an attractive and economical candidate for applications at elevated temperatures.

This study investigated the creep performance, fracture characteristics, and creep mechanisms of the nickel-base single crystal superalloy DD406 under conditions of 1100°C and 140MPa. The results indicate that the alloy exhibited a creep life of 104.5 hours and a strain of 33.58%. The creep curve exhibited three distinct stages: initial (deceleration), steady-state, and accelerated creep. The fracture surface was characterized by dimples and tearing edges, with no apparent slip planes. Internal to the fracture, oxidation products and recrystallized structures were observed, and the internal pores exhibited elongated shapes oriented perpendicular to the stress axis. Furthermore, analysis of the creep rate-time curve revealed three sub-stages within the initial (deceleration) creep stage, where the creep rate decreased initially, followed by an increase and subsequent decrease with time.

Thermal management is one of the most promising applications of Al parts fabricated by additive manufacturing, primarily due to the drastically expanded design space enabled by the latter. The thermal properties of additively manufactured Al alloys are crucial for this application but remain poorly understood. The present study focuses on a high-strength Al-Mg-Sc-Zr alloy fabricated by Selective Laser Melting (SLM). The microstructure of the alloy is characterized by optical and electron microscopy, hardness and tensile testing are conducted, and the thermal conductivity and thermal dilatation behavior are tested. The fabricated samples exhibit strong age hardenability and yield strengths reaching similar to 460 MPa. The thermal conductivity in the as-built condition is found to be rather low mainly because of the high solute concentration in the Al matrix as well as the fine grain size, and is improved by 33% after 10 h aging due to precipitation of particles. Meanwhile, abnormal non-linear thermal dilatation behavior is observed in the samples above 400 degrees C, probably related to the expansion of pores. Lastly, orientation dependency with respect to the building direction is found in both thermal conductivity and dilatation, which is associated with the grain alignment and melt pool structures. The above results provide critical knowledge to the process design toward co-optimization of mechanical and thermal properties of Al alloys fabricated by SLM.

The tribological behaviors of Cu-based bulk metallic glass (BMG) Cu50.2Zr40.8Ti8.5Nb0.5 and conventional nickel-aluminum bronze (NAB) reference material were investigated in air and in 3.5% NaCl solution, respectively. The tribology tests were performed at room temperature using a reciprocating tribometer at a sliding speed of 1 m min(-1) against a 6-mm diameter ZrO2 ball. When sliding in air, the friction coefficient of Cu-based BMG decreases with the applied loads (5 N, 10N, and 20 N), and the wear behavior is mainly affected by abrasion, delamination, and oxidation. In particular, the wear-rate of Cu-based BMG is about 22 times lower than that of conventional NAB when sliding in the air under a load of 5 N. When sliding in 3.5 wt% NaCl solution, Cu-based BMG demonstrates better static-corrosion resistance but worse tribocorrosion resistance compared with conventional NAB. Due to the combined effects of corrosion and lubrication caused by the solution, the wear-rate of the BMG in NaCl solution increases at 5 N, but decreases at 20 N when compared with the corresponding wear in air. The tribocorrosion of Cu-based BMG is mainly controlled by abrasive wear and the synergistic effects of abrasion and corrosion. By applying -1.3 V cathodic potential, the corrosive wear-rate of Cu-based BMG at 5 N was reduced by nearly 50%. This work provides an experimental reference for the tribological evaluation of Cu-based BMG in different environments.

The present paper has reported a comparative study on the influence of environmental temperature on the microstructural evolution and tensile mechanical behaviors between squeeze cast (SC) and gravity cast (GC) Mg10Gd-3Y-0.5Zr (GW103K) alloys. The results revealed that for both alloys, the operative deformation mechanisms at testing temperatures (25-300 degrees C) were identified to be (10-12) extension twinning, (10-11) compressive twinning and (10-13) compressive twinning in addition to basal or non-basal slips. The elongation increased monotonically with increasing temperature within the range of 25 degrees C to 300 degrees C. However, the ultimate tensile strength (UTS) abnormally increased (for GC alloys) or keep constant (for SC alloys) with increasing the temperature from 25 degrees C to 250 degrees C, and decreased with further increasing the testing temperature to 300 degrees C. Moreover, at all testing temperature, both the UTS and elongation of the squeeze cast material were improved relative to those of the gravity cast alloy. The underlying mechanism for the abnormal increase of strength within certain elevated temperature range was attributed to the insufficient strain hardening at lower temperatures that restrict further plastic deformation and lead to pre-mature fracture, and sufficient plastic deformation and softening at higher temperatures promote plastic deformation. The strengths improvements in squeeze cast GW103K alloy can be mainly ascribed to the preventing or limiting of crack nucleation sites and hindering of crack propagations through the reduction of micropores and increasing the amount of grain boundaries.