The role of Ce microalloying in regulating the microstructure and coupled corrosion and mechanical responses of CuSn10Zn2Fe1.5Co0.5 alloys was systematically investigated in the as-cast and heat-treated conditions. In the ascast state, Ce markedly modifies the morphology of Fe-rich particles without changing the primary phase constituents, showing a distinct evolution from cube-like to split-petal-like and branched-petal-like features with increasing Ce content. Ce addition is also associated with fragmentation and enrichment of the Sn-rich delta phase, which is consistent with Ce-Sn interaction and altered segregation behavior. During heat treatment, excessive Ce promotes the formation of micron-scale CeP compounds and their aggregation with Fe-bearing particles, accompanied by a reduced population of nanoscale Fe precipitates. These microstructural changes lead to a nonmonotonic property response. A small Ce addition (0.2 wt%) improves corrosion resistance while largely preserving tensile properties, whereas higher Ce levels (>= 0.5 wt%) can cause pronounced reductions in strength and ductility, governed by grain coarsening and damage and fracture controlled by the morphology and grainboundary connectivity of the brittle delta phase network. Corrosion measurements consistently show improved corrosion performance for Ce-containing alloys relative to the Ce-free condition, with the lowest corrosion rate obtained at 0.5 wt% Ce under the present testing conditions. Overall, Ce acts as a composition-dependent microstructural regulator, and the results highlight a clear trade-off between tensile performance and corrosion resistance.

Hot-compression pre-deformation modifies both the segregation length scale and the local defect state of cast GH4169, yet their coupled influence on subsequent chemical homogenization remains unclear. Here, quantitative segregation analysis, EBSD, TEM, and atomistic simulations were combined to compare specimens subjected to 10% and 20% pre-deformation. Increasing the strain further compressed the dendritic/interdendritic framework and intensified local orientation heterogeneity and deformation-induced defect structures. During homogenization at 1160 °C, the 20% condition exhibited lower residual Nb-, Mo-, and Ti-rich segregation than the 10% condition. After 12 h, the as-cast-normalized residual segregation coefficients of Nb, Mo, and Ti reached 0.15, 0.20, and 0.17, respectively, whereas the 10% condition required approximately 16 h to reach comparable values. Within-series normalization further showed more pronounced attenuation of Nb and Ti segregation under 20% pre-deformation, while the strain dependence of Mo was weaker. In a simplified Ni–Nb model, representative defect environments favored vacancy stabilization and Nb accommodation and reduced selected Nb–vacancy exchange barriers. The generic grain-boundary region exhibited a model-specific 1.77-fold higher MSD-derived Nb mobility than the bulk-like region at 1300 K. Within the investigated strain range, the lower residual segregation at higher strain arises from the combined effects of a lower initial segregation amplitude, a shortened redistribution distance, and defect-modified local Nb transport.

This study clarifies how Cu content mediates the coupled effects of Sc addition on recrystallization, precipitation, and mechanical properties in Al-Zn-Mg-Cu alloys processed by a conventional cast-homogenization-hot rolling-solution-T6 route. Four alloys with different Cu and Sc contents were characterized by SEM/EDS, EBSD, XRD, TEM, and tensile testing. Sc addition refined the as-cast grains and promoted the formation of nanoscale L12-Al3(Sc,Zr) dispersoids, which suppressed recrystallization by pinning dislocations and grain/subgrain boundaries. Meanwhile, coarse t)-type, AlCuSc-associated, and Al3(Sc,Zr)-related residual particles were associated with particle-stimulated nucleation. Reducing Cu content in Sc-containing alloys decreased the projected area fraction of coarse residual particles and increased or maintained Mg + Zn solute availability before aging, thereby enhancing intragranular precipitation. Semi-quantitative analysis showed that the relative precipitationstrengthening index increased from 1.00 to 1.88, whereas the relative substructure-strengthening index increased from 1.00 to 1.15, indicating precipitation-dominated strengthening with an additional substructure contribution. Cu1.2Sc0.2 achieved the highest T6 strength, with 631 +/- 7.0 MPa tensile strength, 586 +/- 3.0 MPa yield strength, and 12.2 +/- 0.2% elongation.

This study investigates the influence of crucible configuration on temperature uniformity and energy efficiency in a Lengthwise Graphitization Furnace (LWG). The conventional LWG generally employ cylindrical 9-hole crucibles, with only two crucibles accommodated in a single furnace. However, the circular geometry inevitably creates large gaps between adjacent crucibles, leading to inefficient utilization of the furnace interior space. In this study, a novel square 4-hole crucible configuration is proposed to achieve a more compact crucible arrangement. Compared with the conventional design, this configuration significantly improves the spatial utilization efficiency of the furnace. Two crucible designs-a square 4-hole graphite crucible and a conventional cylindrical 9-hole crucible-were compared through industrial-scale experiments and three-dimensional electrothermal coupled simulations. In the experiments, 61 t of calcined petroleum coke (CPC) powder was used for the 4-hole configuration, while 23.6 t was used for the 9-hole configuration. The numerical model was validated against industrial measurements, with deviations within +/- 5%. Thermal uniformity in the crucible holes was quantitatively evaluated using key indicators, including the temperature difference coefficient and the coefficient of variation. Results show that the 4-hole configuration achieves a more compact layout, reducing inter-crucible voids and resistance material usage. Although the 9-hole design exhibits slightly better single-hole uniformity at certain positions, the 4-hole design increases batch productivity by 2.6 times and lowers specific energy consumption by 33% (7500 vs. 11,200 kWh/t). Energy allocation analysis indicates that at peak product temperature, 21.9% of the total enthalpy is stored in the CPC powder region for the 4-hole configuration, compared to 14.9% for the 9-hole, while the latter retains 44.5% of energy in non-productive furnace structures. Although the 4-hole configuration results in a slight reduction in temperature uniformity, the substantial improvements in productivity and energy efficiency make it more suitable for large-scale industrial production.

To address the high energy consumption of conventional graphitization furnaces, a novel Grid-type Graphitization Furnace (GGF) with a graphite grid container structure was proposed. A combined approach of experimental measurement and numerical simulation was employed to investigate the electrical-thermal characteristics of the furnace during the power supply process. Real-time temperature monitoring was performed throughout the heating process using a customized infrared measurement device capable of accurately detecting ultra-high furnace core temperatures above 2800 degrees C, and an electro-thermal coupled model was established to analyze the distributions of the electric field, temperature field, and heat generation. The simulated results exhibited strong agreement with experimental measurements. Results indicate that the GGF achieves high product quality and excellent temperature uniformity, with temperature differences within 150 degrees C across all spatial directions. Under a furnace loading of 52.2 t, the specific energy consumption for graphitization was 5330 kW & sdot;h & sdot;t-1, corresponding to reductions of 33.4% and 46.7% compared with the Acheson and Lengthwise graphitization furnaces, respectively. The analysis further reveals that the graphite container contributes 60% of the total Joule heat, while the Calcined Petroleum Coke Powder accounts for only 5%. The graphite container transfers heat to the powder, resulting in an overall thermal energy utilization efficiency of approximately 31%. This study provides a validated theoretical and experimental framework for understanding the electrical-thermal behavior of grid-type graphitization furnaces, offering valuable guidance for furnace design optimization, temperature field control, and energy efficiency improvement in large-scale graphitization processes.

Shrinkage and porosity defects critically impair the quality of 12Cr2Mo1V alloy ingots used in high-temperature, high-pressure applications. This study employs finite-element simulations to systematically investigate the effects of pouring temperature, mold preheating temperature, and pouring rate on the filling and solidification behavior of this alloy during low-speed metal mold gravity casting. A numerical model incorporating the Niyama criterion was established and validated against metallographic observations to predict defect formation. The results demonstrate that increasing the pouring temperature from 1535 to 1655 °C causes porosity volume to first decrease and then increase, while defect locations progressively shift away from the riser. Elevating the mold preheating temperature from 150 to 350 °C prolongs solidification time by up to 22

The mechanical properties of M50 steel, which is widely used in aerospace engine bearings, are significantly influenced by its heat treatment process. This study systematically investigates the effects of tempering at different temperatures (450 °C, 480 °C, 510 °C, 540 °C, 570 °C, and 600 °C) on the microstructural evolution and dry sliding wear behavior of Composite Shear Flow Casting (CSFC) M50 steel. The microstructures under various heat treatment conditions were characterized using scanning electron microscopy (SEM), Transmission electron microscope (TEM), and energy-dispersive spectroscopy (EDS). The results show that, with increasing tempering temperature, both the average friction coefficient and wear volume of CSFC-M50 steel initially decrease and then increase. The optimal tribological performance is achieved at 510 °C, with an average friction coefficient of 0.555 and a wear volume of 3.17 × 107 μm3. This trend is attributed to the differing temperature sensitivities of carbide precipitation, which slows down, and carbide coarsening, which accelerates. During the wear process, a dense Cr-rich oxides film forms on the surface via oxidation, acting as a self-lubricating layer that reduces wear and enhances surface resistance. The dominant wear mechanisms include oxidative wear, abrasive wear, and adhesive wear.

The competitive growth of polymorphs during solidification is a fundamental problem governing microstructural evolution and the resulting properties of metals. In this study, we investigate nucleation, competitive growth, and transformation mechanisms among the BCC, FCC, and HCP phases of lead melts using molecular dynamics (MD) simulations combined with well-tempered metadynamics (WTMetaD). Two dominant thermodynamic pathways are unveiled: a one-step liquid-to-FCC transition and a two-step liquid-to-BCC-to-FCC transition. In the two-step pathway, the FCC phase exhibits the fastest crystal growth rate, followed by the BCC phase and then the HCP phase. A substantial population of BCC-like precursors preferentially accumulates at the solid-liquid interface, and the population of BCC-like precursors reaches a maximum during the mid-growth stage. These characteristics of the BCC-like precursors make the BCC phase the second most abundant, surpassed only by the thermodynamically most stable FCC phase during the early solidification process. The thermodynamic analysis indicates that the complex free energy surface provides multiple pathways for solidification, dominating the competition of different polymorphs. These findings provide atomistic insights into the competitive mechanisms among polymorphs during the solidification of FCC metallic systems, and offer a theoretical basis for understanding and controlling polymorph selection during solidification.

Cooling-water pipes in graphitization lines suffer from coupled high-temperature sulfur corrosion and erosion. This study characterizes the axial corrosion gradient of uncoated 310S pipes and evaluates HVOF-sprayed WC-10Co-4Cr coatings (100, 200, 300 mu m). The uncoated pipe shows severe tip corrosion (penetration similar to 316-380 mu m) governed by grain boundary degradation and sulfate-induced depassivation. The 200 mu m coating exhibits the best mechanical integrity (bond strength 82.0 +/- 3.4 MPa, hardness 1295 HV0.1), high-temperature wear resistance (8.8-fold lower wear volume), and corrosion resistance, with continuous coverage confirmed by post-service inspection.

Refinement of the solidification microstructure is critical for mitigating macrosegregation, minimizing casting defects, and enhancing the mechanical isotropy of high-strength low-alloy steels. To achieve this, 35CrNi3MoVNb steel ingots were fabricated using a novel composite shear flow casting (CSFC) technique. This method utilizes simultaneous mold rotation and revolution to induce multidirectional melt flow. Microstructural characterizations and transient fluid-thermal numerical simulations were conducted to elucidate the refinement mechanisms. The results demonstrate that the CSFC process significantly refines the as-cast microstructure. Specifically, the columnar-to-equiaxed transition (CET) shifts prominently towards the ingot surface (from z = 95 mm to z = 33 mm). The underlying fluid-thermal synergistic mechanisms are twofold. The intense tangential shear flow generates substantial bending stresses (4.62 to 28.87 MPa), effectively fractures the growing columnar dendrites, and leads to the formation of dendrite fragments. The radial shear flow transports these fragments into the bulk melt and rapidly dissipates the central superheat, reducing the macroscopic temperature gradient to negligible levels (G ≈ 0 K/mm). This homogenized thermal environment creates the thermodynamic prerequisite for the survival and subsequent multiplication of equiaxed grains. This work elucidates the synergistic mechanical-thermal mechanisms of CSFC, providing an innovative paradigm for manufacturing highly homogeneous CrNiMoV alloy ingots.

Quenching is a critical heat treatment process for thick-walled, variable-cross-section pipes. Traditional resistance-heating methods suffer from several drawbacks, including austenite grain coarsening in thin-wall segments, low heating efficiency, high energy consumption, and lengthy processing times. This study investigated induction heating as an alternative approach, to achieve rapid and uniform heating of such workpieces before hardening. An induction heating model was established, which integrated multi-zoned heating approach into an inductor with open/closeable structure, to explore the optimal heating parameters and dynamic power-control strategies. The results showed that using a closed-loop dynamic power control method based on the workpiece temperature feedback, adjusted the activated current (8000A-16000A, 300Hz) and idle current (70 % of activated magnitude, 300Hz) in real time, ensured the radial temperature distribution of the workpiece met production requirements within 40min.The incorporation of magnetic flux concentrator and heat treatment ring effectively minimized temperature differences around the step part. Applying higher power input addressed the low-temperature issues at the workpiece ends. Ultimately, the overall temperature variation of the workpiece was maintained within 860 degrees C +/- 20 degrees C, with a uniform temperature zone proportion reaching 95 % (3800 mm/4000 mm) along the axial direction. The reliability of the analysis model was verified by an induction heating experiment. The findings indicate a practical pathway for improving ongoing heat-treatment workflows.

High-carbon high-chromium cold-work die steels are strongly affected by detrimental microstructural inheritance from traditional gravity casting, including coarse columnar grains, elemental segregation, and continuous network-like eutectic carbides. In this work, compound shear-flow casting (CSFC) was proposed as a solidification-control strategy to regulate the as-cast microstructure of Cr12MoV steel and mitigate these inherited defects. The thermal-flow field, solidification macrostructure, eutectic-carbide distribution, heat-treated microstructure, and mechanical properties of CSFC-processed steel were systematically compared with those of traditional gravity casting (TGC) steel. CFD simulations show that CSFC transforms melt flow from thermally driven natural convection to mechanically imposed forced convection, thereby reducing residual superheat, compressing the thermal boundary layer, and homogenizing the temperature field. Consequently, the classical chill-columnar-equiaxed three-zone structure is largely suppressed: the central equiaxed-zone fraction increases from 28.4% to 77.19%, whereas the columnar-zone fraction decreases from 68.25% to 16.9%. EBSD and optical microscopy confirm that CSFC refines the radial grain structure and converts coarse network-like or herringbone-like eutectic carbides into finer and more dispersed carbide constituents. After identical forging and heat treatment, the CSFC steel retains these microstructural advantages, forming a finer tempered-martensitic microstructure with refined undissolved carbides and smaller prior-austenite grains. Accordingly, its impact absorbed energy and flexural strength reach 17.28 ± 0.37 J and 2038 ± 7.97 MPa, increasing by 29.5% and 5.5%, respectively. These results demonstrate that CSFC effectively suppresses detrimental microstructural inheritance and provides a promising route for producing high-performance Cr12MoV cold-work die steel.

This study investigates the effect of nitrogen alloying on the phase evolution, microstructure, and mechanical performance of the Al0.5CoCrFeMnNi high-entropy alloy in three distinct processing conditions: the as-cast and homogenized states, the annealed state after cold rolling, and the welded state. Nitrogen promotes the formation of AlN precipitates, which consume aluminum and suppress the precipitation of the brittle Ni-Al-rich B2 phase, thereby stabilizing a single-phase face-centered cubic matrix. In the annealed condition following cold rolling, nitrogen reduces Zener pinning and twin boundary density, facilitating grain growth and enhancing dislocation-based hardening. In the welded condition, nitrogen significantly modifies solidification behavior, refines the fusion zone by promoting equiaxed grains, and mitigates twin boundary elimination in the heat-affected zone. As a result, the nitrogen-alloyed weld achieves a 154.9 % increase in ductility compared to its nitrogen-free counterpart, while maintaining adequate strength. Fractography confirms a transition from mixed-mode to fully ductile fracture. These findings demonstrate that nitrogen serves as an effective alloying strategy to regulate phase stability, precipitation behavior, and mechanical performance across multiple processing pathways in dual-phase HEAs.

M50 steel, known for its excellent high-temperature mechanical properties, is widely used in critical components such as high-speed bearings. However, during hot working, it tends to exhibit coarse microstructures and uneven performance, compromising service reliability. To address this, hot compression experiments were systematically conducted to investigate its deformation behavior and optimize the hot working process. True stress-strain curves were obtained under deformation temperatures ranging from 890 degrees C to 1130 degrees C and strain rates of 0.05-10 s(-1). The activation energy for hot deformation was calculated to be 363,504 J/mol, and a constitutive model with high prediction accuracy was established, showing a correlation coefficient of 99.3 % with experimental results. A hot processing map was developed by combining power dissipation efficiency and flow instability criteria, identifying a stable DRX region at high temperatures and low strain rates. Taking grain refinement and stability into account, the hot working window was narrowed to 1030-1130 degrees C and 0.05-0.50 s(-1), yielding an average grain size of similar to 2.54 mu m. The results also indicated that increasing temperature or strain rate promotes DRX; under constant temperature, grain size decreases with increasing strain rate, while under constant strain rate, it increases with temperature. Excessively high strain rates may lead to stress concentration, abnormal grain growth, and reduced processing stability. Furthermore, a CA model based on the constitutive equation was developed to predict microstructural evolution. The simulation results agreed well with experimental data, confirming the model's accuracy and effectiveness in simulating the DRX behavior of M50 steel.

This study demonstrates that the complex shear flow casting (CSFC) method not only promotes significant alpha-Al grain refinement and the formation of Si nanoparticles in the Al matrix, but also induces finer sub-grain structures within alpha-Al, ultimately resulting in a hierarchical nanostructure in the Al-7 wt% Si alloy. These findings highlight the potential of the CSFC method for scalable grain refinement and performance enhancement in cast aluminum alloys.

Resistance heating of variable cross-section pipes before quenching can cause austenite grain coarsening, leading to inferior properties in thin-wall segments. This method also suffers from low heating efficiency, high energy consumption, and is time-consuming. This study compared the effects of variable cross section (VCS) and equal cross section (ECS) coil structures on overall continuous induction heating, aiming to investigate rapid and uniform heating solutions for this type of pipe. The results showed that the workpiece could be heated to the quenching temperature of 890 degrees C within 30 min using both coils. The ECS coil demonstrated superior heating efficiency, while the VCS coil exhibited better heating quality along the axial direction. Optimizations in VCS coil, including dynamic power control and insulation measures significantly improved the heating quality, with the final temperature distribution of the workpiece basically meeting the quenching requirements. Furthermore, an induction heating experiment was conducted to validate the reliability of the analysis model, showing good alignment with the simulated results. Overall, the application of half-open coil induction heating for variable cross-section pipes is feasible, offering a high efficiency and qualified heating quality. However, this technology is better suited for large-scale manufacturing, as each coil structure can only match one product specification; otherwise, it could significantly increase equipment costs. Additionally, for heating large workpieces, the workshop should have sufficient electrical load capacity to meet the power supply requirements.

Molecular dynamics (MD) simulations were employed to investigate the effects of hydrostatic pressure on nucleation and grain growth in Al-7Si alloy during isothermal solidification. The mean first-passage time (MFPT) method was used to calculate the nucleation rate and critical nucleus size under varying hydrostatic pressures. The growth exponent was determined to assess the grain growth rate. The Johnson-Mehl-Avrami (JMA) method was applied to calculate the Avrami exponent, and the grain size after solidification was statistically analyzed. Uniaxial tensile simulations were performed to evaluate the mechanical properties of the Al-7Si alloy post-solidification. The results show that as hydrostatic pressure increases during solidification, the nucleation rate rises, while the critical nucleus radius remains nearly constant. Increased pressure slows the grain growth rate, inhibits grain growth, reduces the average grain size after solidification, and improves the overall mechanical properties of the Al-7Si alloy. These findings have significant scientific and engineering implications for Al-7Si alloys, providing valuable insights into the role of hydrostatic pressure in refining microstructures and enhancing material properties for various industrial applications.

A series of as-cast SixAl0.43CoCrFeNi2.1 (x = 0, 0.1, 0.2, and 0.3) high-entropy alloys (HEAs) was successfully fabricated by vacuum-assisted melting. The phase constituents, microstructural features, and mechanical properties (including hardness, tensile behavior, and wear behavior) of alloys with various Si contents were evaluated. The results revealed that the addition of Si promoted the precipitation of a body-centered cubic 1 (BCC1) phase enriched in Al, Ni, and Si with a B2-ordered structure. Furthermore, the secondary BCC2 phase was enriched with Cr, Fe, and Si precipitates within the BCC1 matrix. Ultimately, a multiphase face-centered cubic (FCC)/(BCC1/BCC2) structure was formed. The microstructural evolution driven by Si addition significantly enhanced the mechanical properties of the SixAl0.43CoCrFeNi2.1 HEAs. As the Si content increased, the microhardness and tensile strength improved by approximately 42

Porous materials have a wide range of applications in the adsorption of pollutants. In this study, porous geopolymer (PG) was prepared by using steel slag and fly ash as raw materials. The changes in the mechanical properties, microstructure, and methylene blue (MB) removal rate of PG caused by carbonation were observed. The results showed that the filling of CaCO3 and the increase of polymerization degree led to the increase of PG compressive strength during carbonation, and the compressive strength of carbonated PG reached 2.27 MPa. According to BET and XPS results, carbonation resulted in an increase in the specific surface area and surface hydroxyl functional groups of PG. Compared to non-carbonated PG, there was a 34% increase in the removal rate and adsorption capacity of MB. The maximum adsorption capacity of MB by carbonated PG was 27.61 mg/g. Additionally, FTIR analyses suggested that the electrostatic interactions and hydrogen bonding were the primary dye adsorption mechanisms, and the MB adsorption by carbonated PG conformed to fit the Freundlich isotherm and pseudo-second-order kinetic models.