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<p>Upon approaching 850&#xa0;°C, the GH4151 alloy exhibits diminished high-temperature strength, primarily attributed to the disruption of γ′ phase coherence at elevated temperatures, which reduces its strengthening contribution. Tantalum (Ta) additions enhance the stability of the γ′ phase but introduce processing challenges, including pronounced solidification segregation, the formation of secondary phases, and increased susceptibility to cracking during processing. The influence of Ta content on elemental segregation, solidification microstructure, phase precipitation kinetics, and hot deformation behaviour in GH4151 was systematically investigated. Processing windows derived from the dynamic materials model (DMM) and microstructural evolution under varying thermomechanical conditions are further examined. Key findings reveal the severe Ta segregation (segregation coefficient <i>K</i> ≈ 1.608); Ta promotes γ/γ′ eutectic and η phase formation, increasing γ′ phase volume fraction from 54% to approximately 63%; and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window; optimized thermomechanical processing parameters (elevated temperatures and strain rates) enhance recrystallization kinetics and hot workability, thereby mitigating cracking propensity.</p>

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Solidification microstructure and heat deformation characteristics of hard-to-deform superalloy GH4151

  • 期刊论文

  • 发表日期：

    2025年9月25日

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  • Shuai Ren,
  • Shao-min Lyu,
  • Xing-fei Xie,
  • Wei-xue Hou,
  • Jing-long Qu,
  • Jin-hui Du

摘要

Upon approaching 850 °C, the GH4151 alloy exhibits diminished high-temperature strength, primarily attributed to the disruption of γ′ phase coherence at elevated temperatures, which reduces its strengthening contribution. Tantalum (Ta) additions enhance the stability of the γ′ phase but introduce processing challenges, including pronounced solidification segregation, the formation of secondary phases, and increased susceptibility to cracking during processing. The influence of Ta content on elemental segregation, solidification microstructure, phase precipitation kinetics, and hot deformation behaviour in GH4151 was systematically investigated. Processing windows derived from the dynamic materials model (DMM) and microstructural evolution under varying thermomechanical conditions are further examined. Key findings reveal the severe Ta segregation (segregation coefficient K ≈ 1.608); Ta promotes γ/γ′ eutectic and η phase formation, increasing γ′ phase volume fraction from 54% to approximately 63%; and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window; optimized thermomechanical processing parameters (elevated temperatures and strain rates) enhance recrystallization kinetics and hot workability, thereby mitigating cracking propensity.