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<p>High-entropy carbide (HEC) ceramic–iron matrix composite coatings with varying Ti contents, denoted as (Ti<sub><i>x</i></sub>WMoNbV)C, were in situ fabricated on high-chromium cast iron via self-propagating high-temperature synthesis (SHS). Thermodynamic parameters, including mixing entropy (<i>Δ</i>S<sub>mix</sub>), mixing enthalpy (<i>Δ</i>H<sub>mix</sub>), atomic size difference (<i>δ</i>), and the <i>Ω</i> parameter, confirm that all investigated compositions meet the criteria for forming high-entropy solid solutions. X-ray diffraction (XRD) analysis indicates that the coatings are predominantly composed of a NaCl-type high-entropy MC phase, along with γ-Fe, α-Fe, and alloyed M<sub>7</sub>C<sub>3</sub> phases. As the Ti content increases, the MC diffraction peaks progressively shift toward higher angles, accompanied by a reduction in lattice parameters. Microstructural characterization reveals that the MC phase evolves from coarse agglomerates at x = 0.35 to a finer and more homogeneous distribution at x = 0.40. However, secondary precipitation and localized coarsening are observed when x ≥ 0.45. The coating with x = 0.40 exhibits the highest average microhardness (1217&#xa0;HV1) and the lowest wear mass loss (0.0221&#xa0;g), indicating superior wear resistance. Electrochemical testing in a 3.5 wt.% NaCl solution demonstrates that all coatings exhibit typical activation–passivation–superpassivation–transpassivation behavior. The incorporation of Ti enhances passivation stability and improves resistance to pitting corrosion. Corrosion preferentially initiates at grain boundaries and in regions associated with M<sub>7</sub>C<sub>3</sub> phases, whereas the high-entropy MC phase remains comparatively stable. Overall, the optimal Ti content range for achieving a balanced combination of hardness, wear resistance, and corrosion resistance is x = 0.40–0.45.</p>

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Effect of Titanium Content on Microstructure and Properties of (TixWMoNbV)C High-Entropy Carbide Ceramic–Iron Matrix Composite Coatings

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • Xiaoyu Ma,
  • Jun Cheng,
  • Lingbo Zhao,
  • Zihan Zhao,
  • Likang Yang,
  • Donghua Dai

摘要

High-entropy carbide (HEC) ceramic–iron matrix composite coatings with varying Ti contents, denoted as (TixWMoNbV)C, were in situ fabricated on high-chromium cast iron via self-propagating high-temperature synthesis (SHS). Thermodynamic parameters, including mixing entropy (ΔSmix), mixing enthalpy (ΔHmix), atomic size difference (δ), and the Ω parameter, confirm that all investigated compositions meet the criteria for forming high-entropy solid solutions. X-ray diffraction (XRD) analysis indicates that the coatings are predominantly composed of a NaCl-type high-entropy MC phase, along with γ-Fe, α-Fe, and alloyed M7C3 phases. As the Ti content increases, the MC diffraction peaks progressively shift toward higher angles, accompanied by a reduction in lattice parameters. Microstructural characterization reveals that the MC phase evolves from coarse agglomerates at x = 0.35 to a finer and more homogeneous distribution at x = 0.40. However, secondary precipitation and localized coarsening are observed when x ≥ 0.45. The coating with x = 0.40 exhibits the highest average microhardness (1217 HV1) and the lowest wear mass loss (0.0221 g), indicating superior wear resistance. Electrochemical testing in a 3.5 wt.% NaCl solution demonstrates that all coatings exhibit typical activation–passivation–superpassivation–transpassivation behavior. The incorporation of Ti enhances passivation stability and improves resistance to pitting corrosion. Corrosion preferentially initiates at grain boundaries and in regions associated with M7C3 phases, whereas the high-entropy MC phase remains comparatively stable. Overall, the optimal Ti content range for achieving a balanced combination of hardness, wear resistance, and corrosion resistance is x = 0.40–0.45.