Journal of Materials Science最新文献

Material extrusion additive manufacturing of metals (MEX/M) often suffers from residual porosity after printing and pressureless sintering, limiting mechanical performance. This study investigates the influence of boron (B) addition (0, 0.3 and 0.6 wt%) and sintering temperature (1200, 1250 and 1300 °C) on the densification, microstructure, and wear behaviour of filament-based MEX/M-fabricated 316L stainless steel. B promotes liquid-phase sintering through the formation of core–shell inclusions and Cr₂B-based liquid phases, leading to enhanced densification at elevated sintering temperatures. Increased B content significantly raises hardness, primarily governed by the extent of Cr₂B formation. Under dry reciprocating wear, the coefficient of friction (COF) decreases with increasing sintering temperature, while B addition produces a temperature-dependent effect, increasing friction at intermediate temperatures but reducing it at higher temperatures. Wear resistance improves consistently with both increasing B content and sintering temperature, with optimal performance achieved at moderate to high B levels under high-temperature sintering conditions. The dominant wear mechanism transitions from adhesive–oxidative to abrasive with increasing B content and sintering temperature. Overall, the improved wear resistance is attributed to enhanced load-bearing capacity and microstructural strengthening associated with B-assisted liquid-phase sintering. These results highlight the effectiveness of B addition as a strategy for improving the tribological performance of MEX/M 316L stainless steel.

Graphical Abstract

Oxide scale formation during thin-slab continuous casting has a complex structure, which is influenced by mold flux contamination, that modifies interfacial reactions during solidification, subsequent reheating, and descaling. While individual aspects of the oxidation behavior of carbon steel have been previously examined, the synergetic effects of mold flux contamination during continuous casting and subsequent reheating on scale modification and the efficiency of hydraulic descaling remain inadequately studied. This study quantitatively examines the effect of flux composition on oxide scale evolution, adhesion, and hydraulic removal in low-carbon steel under simulated industrial conditions. Slab samples with as-cast, cleaned, and flux-coated surfaces were reheated to 1065 °C in a controlled oxidizing atmosphere and immediately descaled using a computer numerical control (CNC)-controlled high-pressure water-jet system. The developed procedures closely simulate industrial conditions. The resulting scale morphologies and residuals after descaling were analyzed using cross-sectional scanning electron microscopy (SEM), Raman spectroscope and quantified through image J analysis. The results demonstrate that the mold flux composition significantly affects the structural evolution and adhesion characteristics of the oxide scale, thereby influencing its hydraulic removal performance.

Cu–Ni–Al ternary alloys are typical coherent precipitation-strengthened systems, whose mechanical properties are strongly influenced by the morphology, size and volume fraction of the L1₂-γ′ phase. This study focused on the effects of various heat treatment processes on its microstructure and mechanical properties, as well as thoroughly analyzing the tensile deformation mechanism. The results show that both aging routes produce the γ matrix and coherent L1₂-γ′ precipitates, but with distinct microstructural characteristics. After low-temperature aging, the L1₂-γ' phase exhibits smaller dimensions and displays spherical or lamellar-like morphologies, accompanied by a high density of annealing twins. In the high-temperature aged alloy, it exhibits increased size and is predominantly cubic in shape. With increasing Cu content, the number of annealing twins and the volume fraction of lamellar-like L1₂-γ′ phases decrease under low-temperature aging, while under high-temperature aging, the precipitate morphology shifts gradually from cubic to spherical alongside reduced precipitation content. The cubic L1₂-γ′ phase provides stronger precipitation strengthening, exhibits a pronounced Bauschinger effect and markedly hinders dislocation motion, leading to the formation of anti-phase domain boundaries and accumulation of edge dislocations upon shearing. Conversely, the spherical or lamellar-like L1₂-γ′ phases contribute less to strength but enhance ductility, with deformed microstructures revealing planar dislocation slip and visible slip traces. Furthermore, serrated grain boundaries from discontinuous precipitation in high-temperature aged alloys intensify local stress concentration, facilitating crack initiation and propagation. These findings provide guidance for tailoring mechanical performance of coherent precipitation-strengthened Cu–Ni–Al alloys through controlled aging and composition design.

In this study, we developed a dual-stimuli-responsive drug delivery system based on TiO₂ nanotube arrays (TNTs) modified with zeolitic imidazolate framework-8 (ZIF-8) and copper sulfide nanoparticles (CuS) for improved antibacterial efficacy and osseointegration. Vancomycin and CuS were co-loaded into the TNTs via a one-pot synthesis approach, and ZIF-8 served as both a high-capacity drug reservoir and a pH-responsive gatekeeper. The system exhibited rapid and controlled drug release under near-infrared (NIR, 808 nm) irradiation and acidic conditions, mimicking post-surgical infection sites. The CuS nanoparticles enhanced photothermal conversion efficiency, thereby promoting ZIF-8 decomposition and accelerating drug release. In vitro tests demonstrated significant antibacterial activity against E. coli and S. aureus, strong anti-inflammatory effects, and excellent cytocompatibility with MC3T3-E1 osteoblast cells. This multifunctional implant surface provides an effective strategy for infection control and bone regeneration in orthopedic applications.

Graphical abstract

Contemporary investigations into 1xxx-series aluminum alloys have concentrated on the microstructural and property responses to synchronous cold and hot rolling, as well as to subsequent intermediate annealing, whereas the effect of post-deformation annealing temperature on asynchronously warm-rolled 1100 alloy remains largely unexplored. Annealing temperature exerts a decisive control over dislocation density, recrystallization kinetics, grain size, grain boundary character, crystallographic texture, and second-phase distribution in warm-rolled alloys, thereby dictating the resultant mechanical behavior. This study employed transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and universal mechanical testing. These techniques were used to characterize the as-cast microstructure and to elucidate the microstructural evolution and mechanical response of asynchronously warm-rolled 1100 aluminum during isothermal annealing for 1 h at temperatures between 250 and 450 °C. Elongation exhibits a non-monotonic variation, initially increasing and then decreasing with rising temperature, while yield strength progressively declines. Tensile strength displays a more complex trend, decreasing first, recovering, and finally decreasing again. The maximum elongation combined with acceptable tensile strength is attained after annealing at 350 °C for 1 h. This superior elongation is attributed to the lowest dislocation density, a high recrystallized volume fraction, finely dispersed second-phase particles, uniformly distributed and moderately deep dimples, and a balanced intensity of major texture components, collectively reducing stress localization. The transient strength recovery is ascribed to second-phase strengthening via the fine second-phase dispersion and to an increased volume fraction of the Rotated Cube{001} < 110 > recrystallization texture.

Zirconium hydride is a commonly used neutron moderator material in compact nuclear reactors; however, its cracking behavior under irradiation conditions remains inadequately characterized. In this work, the irradiation-induced cracking behavior of zirconium hydride was systematically investigated through a combination of SRIM-based damage simulations and controlled deuterium ion irradiation experiments. The results demonstrate a pronounced dose-dependent increase in cumulative crack length over the irradiation damage range (0.16–31.27 dpa). At low doses (0.16–2.02 dpa), both the number and total length of cracks increase significantly, primarily due to grain coarsening, crack nucleation, and accelerated crack propagation. In contrast, at higher doses (18.94–31.27 dpa), the number of cracks tends to saturate and the increase in crack length slows down, indicating that crack propagation mainly occurs through the slow growth of existing crack structures. This work reveals the irradiation-induced cracking mechanism in zirconium hydride and provide critical support for its safe application in advanced reactor environments.

Ni60 alloy is extensively utilized to enhance substrate surface properties owing to its high hardness and superior wear and corrosion resistance. However, its high crack sensitivity, especially during the fabrication of thick cladding layers, severely restricts practical applications. To solve this problem, this study adopted laser cladding to fabricate crack-free high-thickness Ni60 cladding layers on 1Cr18Ni9 steel. Cracking was effectively suppressed by optimizing laser power and substrate preheating temperature. The microstructure evolution, cracking suppression mechanism, mechanical properties, and tribological properties of the cladding layers were systematically investigated. Through synergistic parameter control, a 4.2 mm crack-free cladding layer was successfully achieved. The preheated multilayer cladding samples consist of a γ-Ni matrix, Ni₃B, Cr₇C₃, CrB, and minor Cr₂₃C₆, which contribute to their enhanced performance. Fine equiaxed grains dominated the cladding zone, whereas columnar grains prevailed in the overlap region. Lower laser power promotes finer grains and more abundant CrB precipitation. The 1400 W double-layer cladding layer exhibited the highest microhardness (750 HV_0.5, ~ 4 times that of the substrate) via CrB reinforcement and grain refinement. This condition also achieved the lowest wear weight loss ratio (9.6 × 10^–5), the narrowest and shallowest wear scars, and superior wear resistance governed by abrasive, fatigue, and mild oxidative wear. All cladding layers exhibited interfacial bonding strengths exceeding the cohesive strength of the cladding, with the 1400 W cladding layer reaching over 383 MPa. Overall, this study addresses the major challenge of cracking in thick Ni60 cladding layers and establishes distinct microstructure-property-wear relationships, providing a promising strategy for enhancing wear resistance and facilitating the reliable repair of stainless steel components.

As the world moves more rapidly towards electrification and carbon–neutral energy sources, there is a growing need for sustainable, high-performance energy storage systems to support electric vehicles, wearable electronics, and smart grids. This has been driven by the fact that developed supercapacitors have become the focal point, as they alone offer high charge–discharge speed, high cycling stability, and environmental friendliness. Supercapacitors, as bridges between conventional capacitors and batteries, are nowadays considered enabling technology for next-generation portable and grid-scale energy solutions. However, their practical application as supercapacitors (SCs) is limited by restacking, oxidation, and limited capacitance retention. This review provides an in-depth discussion of current studies on MXene production, focusing on the top-down and bottom-up approaches used to synthesize Ti₃C₂T_x nanosheets. This paper will examine methods to enhance electrochemical performance, particularly by integrating carbon nanostructures, polymers, and metal oxide compounds. The analysis is conducted across different dimensional structures, starting with 0D carbon dots and progressing to 3D porous networks, to assess their role in addressing key bottlenecks. The review identifies known issues in stability, scale-up, and device integration, and proposes future research directions to improve the performance of MXene-based hybrid materials. This work integrates expertise in synthesis, materials engineering, and device-level design to guide the development of next-generation MXene-based supercapacitor architectures.