Alloy Layer Research Articles

An autotransferable alloy overlayer toward stable sodium metal anodes

Sodium (Na) metal anodes receive significant attention due to their high theoretical specific energy and cost-effectiveness. However, the high reactivity of Na foil anodes and the irregular surfaces have posed challenges to the operability and reliability of Na metals in battery applications. In the absence of inert environmental protection conditions, constructing a uniform, dense, and sodiophilic Na metal anode surface is crucial for homogenizing Na deposition, but remains less-explored. Herein, we fabricated a Tin (Sn) nanoparticle-assembled film conforming to separator pores, which provided ample space for accommodating volumetric expansion during the Na alloying process. Subsequently, a seamless Na-Sn alloy overlayer was formed and transferred onto the Na foil during Na plating through a separator-assisted technique, thereby overcoming conventional operational limitations of metallic Na. As compared to traditional volumetrically expanded cracked ones, the present autotransferable, highly sodiophilic, ion-conductive, and seamless Na-Sn alloy overlayer serves as uniform nucleation sites, thereby reducing nucleation and diffusion barriers and facilitating the compact deposition of metallic Na. Consequently, the autotransferable alloy layer enables a high average Coulombic efficiency of 99.9 % at 3.0 mA cm−2 and 3.0 mAh cm−2 in the half cells as well as minimal polarization overpotentials in symmetric cells, both during prolonged cycling 1200 h. Furthermore, the assembled Na||Sn-1.0h-PP||Na3V2(PO4)3@C@CNTs full cell delivers high capacity retention of 97.5 % after 200 cycles at a high cathodic mass loading.

Microstructure evolution and bending fracture mechanism of as-rolled gradient-laminated network titanium matrix composites

Titanium matrix composites (TMCs) have drawn significant interest due to decent specific strength and heat resistance. Introducing gradient and laminated structure can effectively enhance the toughness of TMCs. To achieve sheet forming, the gradient-laminated network titanium boride reinforced Ti6Al4V (TiB/TC4) composite was fabricated by low-energy milling, powder stacking, vacuum hot pressing sintering and β-phase-region hot rolling. After hot rolling, the layer thickness decreased, the layer interface was kept straight, and no macroscopic defects were observed. In the meanwhile, the flattened network structure, rotation and fracture of TiB whiskers, and grain refining of the matrix were observed. TiB whiskers can also promote the dynamic recrystallization of nearby matrix and tend to maintain orientation relations. While retaining the gradient-laminated network structure, the bending strength of the composite was enhanced to 2205 MPa after hot rolling, which is 13.07% higher than that of the as-sintered composite. The strengthening was attributed to grain refining of the matrix and alignment-induced load transfer strengthening of TiB whiskers. Digital image correlation (DIC) revealed the upward movement of the neutral surface away from the center during the bending test, which led to increased tensile stress and crack initiation in the center layer, rather than the region with maximum tensile strain. Upon observing the fracture side face, the crack propagation path was determined to be influenced by layer interfaces, the network structure connectivity, and the outmost alloy layers.

In Vitro Inflammatory Cell-Induced Corrosion Using a Lymphocyte and Macrophage Coculture

BackgroundCobalt-chromium-molybdenum (CoCrMo) and titanium alloys have been used for orthopaedic implants for decades. However, recent evidence has shown that inflammatory cell-induced corrosion (ICIC) can damage these metal alloys. This study aimed to investigate the mechanisms of ICIC by coculturing macrophages with lymphocytes. We hypothesized that macrophages would be able to alter the surface oxide layer of CoCrMo and titanium alloy (Ti6Al4V) disks, with greater oxide layer damage occurring in groups with a coculture compared to a macrophage monoculture and in groups with inflammatory activators compared to nonactivated groups. MethodsMurine macrophages were cultured on American Society for Testing and Materials F1537 CoCrMo and F136 Ti6Al4V disks for 30 days and activated with interferon gamma and lipopolysaccharide. Interferon gamma and lipopolysaccharide were added to the culture medium to simulate local inflammation. Macrophages were either cultured alone or in a coculture with T helper lymphocytes. After the 30-day experiment, scanning electron microscopy was used to examine the disk surfaces, and oxide levels were found using energy dispersive x-ray spectroscopy. ResultsPitting features consistent with previous reports of ICIC were found on disks cultured with cells. Both CoCrMo and Ti6Al4V disks had significantly lower oxide levels in all groups with cells compared to control groups with no cells (P < .01). Additionally, CoCrMo disks had significantly lower oxide levels when cultured with activated macrophages and lymphocytes compared to nonactivated macrophages alone (P < .001), activated macrophages alone (P < .01), and nonactivated macrophages and lymphocytes (P < .05). No differences in the oxide levels were found among the Ti6Al4V groups. ConclusionsThis study demonstrates the ability of macrophages to alter the surface chemistry of commonly used orthopaedic alloys. We found that the addition of lymphocytes and a simulated local inflammatory response may contribute to the ICIC of CoCrMo implants.

Dynamic response of TB9/TC4 titanium laminated composite with strong bonding interface

Taking advantage of high strength of a titanium alloy and high ductility of the other one is performed to manufacture titanium laminated composite that is promisingly applied in high strain rate environments, but the challenge of fabricating high bonding interface of the two titanium alloys still needs to be overcome. In this work, the TB9/TC4 titanium laminated composite was successfully prepared by hot rolling. A strong bonding interface was constructed between the layers of TB9 and TC4 titanium alloys, achieving a high shear strength of up to 770 MPa. The dynamic compression of the TB9/TC4 titanium laminated composite under Split Hopkinson Pressure Bar (SHPB) showed that the stress-strain curve of the composite presented a unique dual-peak feature, indicative of an excellent strain hardening capability. The TB9/TC4 interface, characterized by coherent and low interface formation energy, facilitated deformation accommodation between TC4 and TB9 layers. Concurrently, the TB9/TC4 interface hindered the ASBs and triggered dislocation strengthening due to stress concentration, leading to high dynamic strength of the laminated composite.

Novel Penetrated Nucleation Mechanism for Controlled Synthesis of 2D Materials on Metal Substrates

Abstract2D materials have attracted considerable attention in the past decades for their unique properties, making the understanding of their nucleation process key to effective synthesis. Traditional explanations of thin‐film growth, focusing on the competition between atom interactions at the interface and within layers, often fall short of explaining real experimental results. Herein, a penetrated nucleation mechanism is proposed for 2D materials growth on metal substrates, taking into account the role of metal substrate atoms. This approach leads to a better understanding of how the surface shape evolves in two specific ways during growth in real experimental findings. Supported by detailed first‐principles simulations of boron on metal substrates and thermodynamic analyses of other studies involving metals and nonmetals, the above‐proposed mechanism is validated. Moreover, a broad strategy for growing large‐scale 2D materials on metal surfaces without creating undesired alloy layers is also presented, by adjusting the interfacial interactions by surface passivation, validated by existing experiments.

Dealloying of Mg-based alloys for production of self-supporting metallic nanostructures

Dealloying is a proficient technique in the fabrication of nanostructured metals, particularly nanoporous materials, with promising potential for diverse applications. However, the development of robust and self-standing nanostructured metal foils through dealloying presents significant challenges. By generating an alloy layer on the surface of the metal foil, nanostructures can be generated on the metal foil surface through subsequent dealloying. This approach utilizes the inherent flexibility and ductility of the metal foil to ensure self-support. It also allows for the tailoring of the structure and composition of the dealloyed nanostructured metal by manipulation of the phase constitution in the surface alloy layer. In this study, we report a strategy for generating alloy layers on metal foil surfaces through the thermal evaporation of magnesium (Mg) followed by annealing. Upon dealloying the surface alloy layer, we successfully obtain self-supported nanostructured metal foils. Employing copper (Cu) as an example, we demonstrate that Mg can form a Mg–Cu alloy layer on the surface of a Cu foil, where the control over the alloy layer's phase composition and thickness is achieved by adjusting the annealing duration. Furthermore, we investigated the feasibility of this method on nickel (Ni) substrates, including Ni foils and Ni foams. Moreover, by further functionalizing the resulting nanostructured Ni foil, we transformed it into Ni(OH)2/Ni foil and explored its performance in the electrocatalytic oxygen evolution reaction (OER). The resulting catalyst achieved a current density of 10 mA cm−2 at a potential of only 349 mV in a 1 M KOH solution, exhibiting a Tafel slope of 84.52 mV dec−1. Following 10 h of stability testing, the catalyst exhibited negligible degradation in performance. This study provides a convenient and versatile pathway for preparing self-supported nanostructured metals.

Perforation performance and mechanism of a torch utilizing Al/PTFE/Fe2O3/CuO thermite composites

Aluminum-based thermite containing fluorine oxidizers exhibits excellent performance characteristics such as substantial heat release and tunable gas production. In this study, a torch loaded with Al/PTFE/Fe2O3/CuO thermite composites was recently designed to eject high-temperature jets and penetrate 10 mm-thick Q235 steel plates. The reactivity of the loading composites was systematically studied to analyze the perforation mechanism. The microstructure, the flame temperature, and pressure properties of the thermites were tested. The device’s perforation capacity was quantified. The research confirmed the application potential of fluoropolymer-based thermites in the field of metal perforation. The results of the pressure tests suggest that the composites have a synergistic effect on pressure properties, resulting in better peak pressure than single thermite. The fuel-rich thermite exhibited a higher flame temperature and heat of combustion. It is observed that the perforation velocity increased with the increase in flame temperature and peak pressure. By adjusting the Al and PTFE content of the near fuel-rich thermites, the torch with different equivalence ratios exhibited a tunable perforation time ranging from 0.4 s to 5.21 s. It is hypothesized that the formation of the alloy layer on the surface of the metal targets plays a significant role in the perforation process by weakening the strength of the plates and improving the mobility of the molten area. The results provide a new and practical path to designing efficient perforation agents.

Effect of manganese and vanadium additions on the microstructures and two-body abrasive wear behaviors of Fe–B hardfacing alloys

Fe–B wear-resistant alloys often exhibit brittleness and suboptimal wear resistance, making them unsuitable for severe operational conditions. In this study, we incorporated ferromanganese powder and ferrovanadium powder were compounded into the Fe–B wear-resistant alloy by plasma cladding technology. The results indicate that the addition of a minor percentage of vanadium, such as about 2 wt%, does not induce any changes in the phase composition. The alloy layer primarily consists of (Mn,Fe)2B and γ-Fe, with vanadium predominantly dissolving in the primary (Mn,Fe)2B phase. This dissolution enhances the toughness of the hard phase and refines the grain structure. At around 4 wt% vanadium, a spherical VB phase precipitates. This inclusion elevates the impact toughness of the alloy layer. The impact toughness of the high manganese content with 4.69 wt% vanadium is the highest, up to 39.11 J/cm2, which is about 30 %higher than that of the sample without vanadium. As vanadium content rises, both the hardness and wear resistance of the alloy layer improve. The most optimal performance was observed with a manganese content of 20.15 wt% and vanadium at 4.69 wt%, achieving a hardness of 65.5 HRC and wear amounts of 48.1 mg (24 N load) and 85.0 mg (48 N load).

Formation of ceramic coating on VAL10 aluminum alloy surface via laser modification in polysilicate solution

This article presents the results of an experimental study on the physical and mechanical properties of the surface layer of the VAL10 aluminum alloy after pulsed laser treatment, conducted in a bath with an aqueous solution of polysilicates (PS) at various concentrations. Ceramic coatings were produced on specimens measuring 10×10×3 mm. The laser processing of aluminum alloy specimens was carried out using an Nd:YAG laser. The study demonstrates that the quality of the resulting surface and its properties can vary depending on the laser exposure parameters, the concentration of the polysilicate solution, and the overall processing technique. The scattering of radiation by the PS solution layer leads to a significant reduction in surface roughness. In specimens processed in ambient air, the crater sizes on the surface exceeded 400 μm, while for specimens processed in a PS solution, they did not exceed 100 μm. A comparative analysis of the impact of solution concentration on elemental composition was performed. The study also included an investigation of friction characteristics and the measurement of microhardness of the modified surface. The research revealed that surface hardening processes occur as a result of the treatment, associated with the filling of recesses with high-strength oxides. This enabled the creation of a mixture containing silicon carbide and aluminum oxide in the surface layer of the specimens. Furthermore, wear tests of the modified surface were conducted using a “ball–specimen” tribological coupling. Specimens subjected to laser irradiation in a PS solution demonstrated increased wear resistance (a 40 % reduction in wear) and a 30 % decrease in the friction coefficient. Additionally, an increase in microhardness was observed.

Evolution of interfacial phases between Al alloy and high entropy alloy during annealing

While the interfacial phases between Al and high-entropy alloy (HEA) share the same types as that between Al and steel, it has been found previously that the thermal stability of the Al-HEA interfacial phases is significantly higher than that of the Al-steel interfacial phases. To further elucidate the reason for the exceptional thermal stability of Al-HEA interfacial phases, this study investigated the evolution of the interfacial phases formed between Al alloy and FeCoCrNiMn HEA during annealing. An Al-FeCoCrNiMn thin film diffusion couple was extracted from a friction stir lap welding (FSLW) joint by focused ion beam and then annealed at 400 °C. An amorphous layer is formed initially at the interface due to the high strain rate deformation during FSLW. The amorphous layer remained even after prolonged annealing at 400 °C (∼0.72 Tm of Al alloy) for 60 min with very limited thickening (from 50 nm to 55 nm), showing remarkable thermal stability at the relatively high temperature. Al13Fe4-type intermetallic compound (IMC) with the Fe site occupied by Fe, Co, Cr, Ni and Mn first nucleates at the interface between Al alloy and amorphous layer. With the annealing time extended to 180 min, the amorphous layer is partially transformed into Al5Fe2-type IMC. The rate constant for the thickening of the reaction layer at the Al/FeCoCrNiMn interface is 0.03 μm∙min1/2, which is much smaller than (only 0.02 times) that at the Al/steel interface under similar annealing condition. The high thermal stability of Al-HEA interfacial layer is thus attributed to the slow kinetics in crystallization of the initially formed amorphous layer, the barrier effect of amorphous layer for interdiffusion, and the reduced diffusivity inside of IMCs caused by significant fluctuations in lattice potential energy due to high-density doping with HEA elements. This finding provides new insights into the fabrication of thermally stable Al-HEA hybrid structures suitable for service conditions involving high-temperature exposure.

Laser shock peening of laser melting deposited TiAl alloy for enhancing its corrosion resistance

Laser shock peening (LSP), as a post-treatment process, was employed to improve the corrosion resistance of Ti45Al8Nb alloy fabricated via laser melting deposition (LMD). Microstructure analysis indicated that nanograins and nanotwins structures were formed on the surface layer of LSP-treated Ti45Al8Nb alloy, accompanied by high-density dislocations and stacking faults. Electrochemical results showed that LSP improves the corrosion resistance of Ti45Al8Nb alloy. The formation of nanograins, nanotwins and compressive residual stress during LSP was conductive to dense oxidation films, thus improving the corrosion resistance of the as-deposited Ti45Al8Nb alloy.

Construction of an artificial zinc alloy layer toward stable zinc-metal anode

Aqueous zinc-ion batteries (AZIBs) present a promising option for next-generation batteries given their high safety, eco-friendliness, and resource sustainability. Nonetheless, the practical application of zinc anodes is hindered by inevitable parasitic reactions and dendrite growth. Here, zinc alloy layers (i.e., ZnCo and ZnFe alloys) were rationally constructed on the zinc surface by chemical displacement reactions. The alloying process exposes more (002) planes of the ZnCo anode to guide the preferential and dendrite-free zinc deposition. Furthermore, the ZnCo alloy layer not only effectively inhibits water-induced side reactions but also accelerates electrode kinetics, enabling highly reversible zinc plating/stripping. As a result, the ZnCo anode achieves a Coulombic efficiency of 99.2% over 1300 cycles, and the ZnCo symmetric cell exhibits a long cycle life of over 2000 h at 4.4 mA cm−2. Importantly, the ZnCo//NH4V4O10 full cell retains a high discharge capacity of 218.4 mAh g−1 after 800 cycles. Meanwhile, the ZnFe-based symmetric cell also displays excellent cycling stability over 2500 h at 1.77 mA cm−2. This strategy provides a facile anode modification approach toward high-performance AZIBs.

Analysis of the State of the Surface Layer of the SAP-2 Composite Alloy after Irradiation with a High-Power Ion Beam

Analysis of the State of the Surface Layer of the SAP-2 Composite Alloy after Irradiation with a High-Power Ion Beam

The Effect of Carbide Concentration at Grain Boundaries on Thermal Stresses in Castings for Heat Treatment Furnace Tooling

Austenitic Fe-Ni-Cr alloys are commonly used for the production of castings intended for high-temperature applications. One area where Fe-Ni-Cr castings are widely used is the equipment for heat treatment furnaces. Despite the good heat resistance properties of the materials used for the castings, they tend to develop cracks and deformations over time due to cyclic temperature changes experienced under high temperature operating conditions. In the case of carburizing furnace equipment, thermal stresses induced by the temperature gradient in each operating cycle on rapidly cooled elements have a significant influence on the progressive fatigue changes. In the carburized subsurface zone, also the different thermal expansion of the matrix and non-metallic precipitates plays a significant role in stress distribution. This article presents the results of analyses of thermal stresses in the surface and subsurface layer of carburized alloy during cooling, taking into account the simultaneous effect of both mentioned stress sources. The basis for the stress analyzes were the temperature distribution in the cross-section of the cooled element as a function cooling time, determined numerically using FEM. These distributions were taken as the thermal load of the element. The study presents the results of analyses on the influence of carbide concentration increase on stress distribution changes caused by the temperature gradient. The simultaneous consideration of both thermal stress sources, i.e. temperature gradient and different thermal expansions of phases, allowed for obtaining qualitatively closer results than analyzing the stress sources independently

Parameters optimization for laser-cladding CoCrFeNiMn high-entropy alloy layer based on GRNN and NSGA-II

In order to improve the bonding strength of FeCoCrNiMn cladding layer, laser power, scanning speed and powder feeding rate were selected as the optimization variables; the aspect ratio, dilution rate and heat affected zone depth of the cladding layer were selected as the optimization indicators; a three-factor three-level full-factor experiment was designed; a nonlinear model of cladding parameters and cladding performance was established by generalized regression neural network algorithm (GRNN), while the error of prediction value and experimental results was less than 10%. A set of optimal Pareto frontiers were obtained by the Non-Dominance Ordering Genetic Algorithm (NSGA-II), and the optimal individuals were obtained based on the equal weights, and the optimal cladding parameters were as follows: laser power 2.33 kW, scanning speed 2.90 m/min, and powder feeding rate 12.46 g/min. The cladding layer prepared under the optimal parameters has a dense cross-section with no defects such as cracks and porosity. The joint optimization using the GRNN neural network and the NSGA-II genetic algorithm can obtain excellent results, and the relative error between the experimental and predicted values can be controlled within 10%. The application of optimized laser process parameters can significantly improve defects such as poor adhesion, cracks and porosity on the surface of the cladding layer, and also improve the surface hardness and wear resistance. The experimental results show that the wear rate of the cladding layer prepared by the optimized parameters is 3.21×10−5 mm3/N·m, which is 1.5 times higher than that of the cladding layer prepared by P=2.1 kW, V=3 m/min and C=9 g/min. The wear mechanism mainly includes abrasive wear, plastic deformation and oxidative wear.

Synergistic crack inhibition by lamellar structure and graphene nanoplatelets in 2024 Al-GNPs/TC4 laminated metal composites

Al/Ti laminated metal composites (LMCs) benefit from a bionic laminate structure that allows for simultaneous strength and plasticity enhancement. However, the Al layer with lower strength is always the first to crack under stress, resulting in declining mechanical properties of the Al/Ti LMCs. In this study, 2024 Al-GNPs/TC4 LMCs were prepared by replacing the conventional Al or Al alloy layers with 2024 Al-GNPs composites. Its ultimate tensile strength of 757 MPa surpasses that of almost all other Al/Ti LMCs. The lamellar structure and GNPs were found to have a synergistic effect in enhancing the mechanical properties by inhibiting crack extension across and within the layers, respectively. The hindrance of crack extension by the lamellar structure is primarily due to strain delocalization in TC4, as confirmed by phase-field-crystal simulation. On the other hand, GNPs impede crack extension through passivation and deflection, which was revealed by molecular dynamics to be attributed to dislocation hindrance and load transfer. Furthermore, it was confirmed that the main factors affecting the formation of intermetallic compounds are diffusion coefficient and solid solubility. This work provides new insights for breaking the performance limits of LMCs.

New insight into the role of Cu addition on surface nanocrystallization and corrosion behavior of aluminum alloy

Realization of surface-reinforced aluminum alloys with excellent corrosion resistance remains a major topic. Herein, a novel method based on combination of electron beam evaporation plating and surface alloying was proposed. Results revealed that the current density is one order of magnitude less than that of the substrate and that the impedance value is doubled. The nanometer-scale refinement of the grains and the homogenous dispersion of nanocrystallization Al2Cu in the modified layer of aluminum alloy contributed to the enhancement of corrosion resistance. This study is expected to provide a new sight for the development of Cu-reinforced high-performance aluminum alloys.

The Effect of Laser Power on the Microstructure and Wear Resistance of a Ni3Al-Based Alloy Cladding Layer Deposited via Laser Cladding

A coating prepared via laser cladding has the advantages of a high-density reinforced layer, a low matrix dilution rate, and combination with matrix metallurgy. In this study, Ni3Al-based alloy cladding layers with Cr7C3 were prepared via laser cladding, and the corresponding microstructures and wear resistance were studied in detail. The results show that the Ni3Al-based cladding layer prepared using laser cladding technology had good metallurgical bonding with the matrix, and there were no pores, cracks, or other defects on the surface. The microstructures of the laser cladding layer were mainly γ′-Ni3Al, β′-NiAl, and in situ C7C3. As the laser power increased, the heat input increased, resulting in an increase in the dilution rate. Simultaneously, the carbide size in the laser cladding layer increased. With the increase in laser power, the hardness of the laser cladding layer of the Ni3Al-based alloy decreased, and the wear resistance of the laser cladding layer first strengthened and then weakened. When the laser power increased to 2.0 kW, the wear rate of the laser cladding layer decreased to 0.480 × 10−5 mm3/N·m. When the laser power increased to 2.4 kW, the wear rate of the laser cladding layer increased to 0.961 × 10−5 mm3/N·m, which was twice the rate at 2.0 kW. This could be attributed to small Cr7C3 particles, which could not effectively separate the wear pairs, resulting in more serious adhesive wear. Large Cr7C3 particles caused the surface of cast iron material with lower hardness to be damaged, which suffered more serious particle wear. The generation of short rod-shaped carbides should be avoided because, in the process of friction and wear, carbides with these shapes are easy to break, thus leading to crack initiation.

Interface Effect on the Out‐of‐Plane Spin‐Orbit Torque in the Ferromagnetic CoPt Single Layers

AbstractField‐free switching of a perpendicularly magnetized heavy metal/ferromagnetic metal bilayer or single alloy layer through spin‐orbit torque (SOT) provides a potential way for next‐generation spintronic devices with fast speed and high efficiency. Here, a sizable symmetry dependence of field‐free magnetization switching via an out‐of‐plane torque in CoxPt100−x single layers is reported. It is found that the sign of in‐plane SOT in CoxPt100−x when x ≤ 25 is positive. However, it changes to negative when x &gt; 25, while the out‐of‐plane SOT changes its sign when x &gt; 30. The polarized neutron reflectometry measurement further suggests an interface layer with rich Pt content near the substrate, which could have a strong interface effect on the out‐of‐plane SOT. The sign of the out‐of‐plane SOT, and then the polarity of the field‐free magnetization switching, is determined by the competition between the out‐of‐plane torques arising from the bulk and interface parts in the CoxPt100−x single layers. It is expected that such interface effect of the out‐of‐plane torque is desirable to the applications in spin logic devices using symmetry dependence of field‐free magnetization switching in the ferromagnetic CoPt single layers.

A novel class of ATF fuels with large grain size, enhanced thermophysical properties and oxidation resistance

Two strategies have been extensively employed to develop advanced accident tolerant fuels (ATF): improving thermal conductivity and producing large grain sized pellets. However, there are few reports on the simultaneous utilization of both strategies. In this work, we fabricated Mo–Cr alloy reinforced UO2 (UMC) composite pellet with both high thermal conductivity and large grain size by a simple in-situ alloying method for the first time. The average grain size of UO2 increased from 6 μm to 113 μm. Thermal conductivity of the UMC pellet (with 2 vol% Mo) at 1200 °C increased by 36.46% compared with pure UO2. The increase rate of thermal conductivity per 1 vol% dopant reached about 18%. The Mo–Cr alloy formed continuous micro-cell layer around UO2 particles. Such continuous micro-cell Mo–Cr alloy layer and increase of UO2 grain size both helped improve the thermal conductivity of UMC composite pellets. Thermal expansion coefficient of the UMC under the operating temperature decreased by 11.90% compared with pure UO2. The oxidation resistance of the UMC pellet under high temperature steam was also improved. This work provides a new strategy towards fabricating ATF with both high thermal conductivity and large grain size.