Unraveling the formation of L12 nano-precipitates within the FCC-phase in AlCoCrFeNi2.1 eutectic high entropy alloy

J. Charkhchian, A. Zarei-Hanzaki, A. Moshiri, T. M. Schwarz, R. Lawitzki, G. Schmitz, N. Schell, Jiajia Shen, J. P. Oliveira, Daudi Waryoba, H. R. Abedi

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11 Citations (Scopus)

Abstract

The present study investigates the formation mechanism of L12 nano-precipitates within the FCC phase during the solidification process of the AlCoCrFeNi2.1 eutectic high entropy alloy. For this purpose, advanced characterization techniques, including high-energy synchrotron X-ray diffraction, transmission electron microscopy, and atom probe tomography were employed, along with CALPHAD calculations. The solidified microstructure of the AlCoCrFeNi2.1 eutectic high entropy alloy consists of five phases: disordered FCC, disordered BCC, ordered B2 BCC, ordered L12 FCC, and sigma (σ). The dendritic regions of the disordered FCC phase were formed due to non-equilibrium solidification, while the L12 nano-precipitates were uniformly embedded within the disordered FCC matrix. These nano-precipitates were enriched with Al and Ni, while being depleted in Co, Cr, and Fe. These nano-precipitates might form around the critical temperature of 600 °C due to short-range diffusion of Al and Ni because of nucleation and growth mechanism during the solidification process.
Original languageEnglish
Article number112919
Number of pages9
JournalVacuum
Volume221
DOIs
Publication statusPublished - Mar 2024

Keywords

  • Eutectic high entropy alloy
  • L1 nano-precipitates
  • Ordered phase
  • Phase transformation
  • Solidification

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