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<p>The formation of porosity is influenced by multiple factors during solidification process. Through isothermal solidification quenching experiments, differential scanning calorimetry, and microstructural characterization, the evolution of microstructure and element segregation behavior during terminal solidification was studied. The results indicate that severe elemental segregation occurs in GH4151 superalloy during the final solidification stage, leading to a large solidification temperature range of 140&#xa0;°C. Based on measured composition of liquid phase after the formation of isolated liquid, combined with thermodynamic calculations and molecular dynamics simulations, supplemented by directional solidification experiments, the characteristics of residual liquid phase and microstructural characteristic at final stage of solidification were clarified, including large solid–liquid density difference (0.39 g/cm<sup>3</sup>), poor wettability (~ 83 deg), small surface tension (1718.65 mN/m) and small secondary dendrite arm spacing (55 <i>μ</i>m), compared to IN718 superalloy. These features collectively result in intensified volume shrinkage, reduced fluidity, greater critical pressure for porosity formation and narrowed feeding channels during the final solidification stage, thereby significantly increasing the shrinkage porosity tendency. This research reveals the synergistic mechanism of microstructural and liquid phase characteristics at the final stage of solidification in GH4151 on shrinkage porosity susceptibility, providing a theoretical basis for controlling casting defects in multi-component complex superalloys.</p> Graphical Asbtract <p></p>

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Effect of Microstructure and Liquid Characteristics During Final Stage of Solidification on Porosity in a Difficult-to-Deform Superalloy

  • 期刊论文

  • 发表日期：

    2026年4月2日

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  • Shu Li,
  • Jia Zhong,
  • He Jiang,
  • Zhihao Yao,
  • Jianxin Dong

摘要

The formation of porosity is influenced by multiple factors during solidification process. Through isothermal solidification quenching experiments, differential scanning calorimetry, and microstructural characterization, the evolution of microstructure and element segregation behavior during terminal solidification was studied. The results indicate that severe elemental segregation occurs in GH4151 superalloy during the final solidification stage, leading to a large solidification temperature range of 140 °C. Based on measured composition of liquid phase after the formation of isolated liquid, combined with thermodynamic calculations and molecular dynamics simulations, supplemented by directional solidification experiments, the characteristics of residual liquid phase and microstructural characteristic at final stage of solidification were clarified, including large solid–liquid density difference (0.39 g/cm3), poor wettability (~ 83 deg), small surface tension (1718.65 mN/m) and small secondary dendrite arm spacing (55 μm), compared to IN718 superalloy. These features collectively result in intensified volume shrinkage, reduced fluidity, greater critical pressure for porosity formation and narrowed feeding channels during the final solidification stage, thereby significantly increasing the shrinkage porosity tendency. This research reveals the synergistic mechanism of microstructural and liquid phase characteristics at the final stage of solidification in GH4151 on shrinkage porosity susceptibility, providing a theoretical basis for controlling casting defects in multi-component complex superalloys.

Graphical Asbtract