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<p>Cracking presents a major hurdle for processing non-weldable Ni-base superalloys, such as CM247LC, by powder bed fusion–laser beam (PBF–LB). This study directly observes cracking behavior in standard CM247LC and two admixed alloys (CM247LC + 1 wt.% Hf and CM247LC + 1 wt.% nano-Y<sub>2</sub>O<sub>3</sub>) using <i>operando</i> synchrotron X-ray radiography synchronized with acoustic emission (AE). Our real-time data confirm extensive cracking in the standard alloy is identified to be primarily solidification cracking. Both Y<sub>2</sub>O<sub>3</sub> and Hf additions mitigate solidification cracking, though through distinct mechanisms. Nano-Y<sub>2</sub>O<sub>3</sub> addition alters the processing regime from keyhole to conduction mode. Scheil solidification simulations predict a narrower solidification range and lower solidification cracking index (SCI). This indicates that a combination of processing regime shift along with modification in solidification as the primary drivers for crack suppression upon addition of nano-Y<sub>2</sub>O<sub>3</sub>, despite increased lack of fusion and complex oxide formation. Hf-addition mitigated cracking via enhanced segregation at interdendritic regions, promoting beneficial carbides and improved liquid backfilling. Scheil simulations for alloy with Hf-addition predicted low SCI compared to standard CM247LC due to increased liquid availability in final solidification stages. These insights highlight that nearly crack-free PBF–LB of non-weldable superalloys can be achieved through both the powder modifications.</p>

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Unveiling crack mitigation pathways in powder bed fusion–laser beam of CM247LC: an operando X-ray radiography study of Hf and nano-Y2O3 additions

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月3日

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  • Ahmed Fardan,
  • Gowtham Soundarapandiyan,
  • Vigneashwara Pandiyan,
  • Steven Van Petegem,
  • Efthymios Polatidis,
  • Sofia Kazi,
  • Sneha Goel,
  • Camille Pauzon,
  • Federica Marone,
  • Bharat Mehta,
  • Annapaola Parrilli,
  • Håkan Brodin,
  • Eduard Hryha

摘要

Cracking presents a major hurdle for processing non-weldable Ni-base superalloys, such as CM247LC, by powder bed fusion–laser beam (PBF–LB). This study directly observes cracking behavior in standard CM247LC and two admixed alloys (CM247LC + 1 wt.% Hf and CM247LC + 1 wt.% nano-Y2O3) using operando synchrotron X-ray radiography synchronized with acoustic emission (AE). Our real-time data confirm extensive cracking in the standard alloy is identified to be primarily solidification cracking. Both Y2O3 and Hf additions mitigate solidification cracking, though through distinct mechanisms. Nano-Y2O3 addition alters the processing regime from keyhole to conduction mode. Scheil solidification simulations predict a narrower solidification range and lower solidification cracking index (SCI). This indicates that a combination of processing regime shift along with modification in solidification as the primary drivers for crack suppression upon addition of nano-Y2O3, despite increased lack of fusion and complex oxide formation. Hf-addition mitigated cracking via enhanced segregation at interdendritic regions, promoting beneficial carbides and improved liquid backfilling. Scheil simulations for alloy with Hf-addition predicted low SCI compared to standard CM247LC due to increased liquid availability in final solidification stages. These insights highlight that nearly crack-free PBF–LB of non-weldable superalloys can be achieved through both the powder modifications.