High Pressure and High Temperature Exploration of Phase Transformations in Eutectic High Entropy Alloys

ORAL  · Invited

Abstract

Additively manufactured high-entropy alloys are of interest because of their unique combination of high yield strength and large ductility achieved with far-from-equilibrium crystalline phases and micro/nanostructure morphology. This talk with report on the phase transformation and thermal equation of state of the eutectic high-entropy alloys (EHEAs) Al18Co20Cr10Fe10Ni40W2, and Al16.4Co16.4Cr16.4Fe16.4Ni34.4 produced by laser powder-bed fusion (L-PBF). Both EHEAs were studied in diamond anvil cells of pressures over 300GPa using angular dispersive x-ray diffraction (XRD) and in a large-volume Paris–Edinburgh cell using energy-dispersive XRD of temperatures up to 1723K at below 10GPa. The initial dual-phase nanolamellar face-centered cubic (FCC) and body-centered cubic (BCC) structure of each EHEA transforms into a single FCC phase under high pressure, with the BCC-to-FCC phase transformation completing under 20GPa. The FCC phase remained stable up to pressures over 300GPa. The measured thermal equation of state for the FCC phase of the EHEAs is presented alongside melt and recrystallization spectra. The BCC-to-FCC phase transition completion pressure is correlated with the nanolamellae thickness of the BCC layer in the transformation at ambient temperature.

*This material was based upon work supported by the Department of Energy-National Nuclear Security Administration Center of Excellence CAMCSE (Award No. DE-NA0004154). Wen Chen also acknowledged support from the National Science Foundation CAREER Award (No. DMR-2238204) for 3D printing and microstructural characterization of the EHEA in this work. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations were supported by DOE-NNSA’s Office of Experimental Sciences. The imaging portion of this work was performed at the Notre Dame Integrated Imaging Facility with financial support from the U.S. Army Research Office Grant No. W911NF2110045 under the Materials Synthesis & Processing Program, with Dr. Michael P. Bakas and Dr. Andrew Brown as the program managers.

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Publication: Pope, Andrew D., et al. "High-pressure phase transition in 3-D printed nanolamellar high-entropy alloy by imaging and simulation insights." Scientific Reports 14.1 (2024): 16472.

Pope, Andrew D., et al. "Phase stability of a eutectic high entropy alloy under extremes of pressures and temperatures." AIP Advances 14.2 (2024).

Pope, Andrew D., et al. "Nanolamellar phase transition in an additively manufactured eutectic high-entropy alloy under high pressures." AIP Advances 13.3 (2023).

Katagiri, Kento, et al. "Static and shock compression studies of eutectic high-entropy alloy AlCoCrFeNi2. 1 to ultrahigh pressures." Journal of Applied Physics 135.9 (2024).

Chakrabarty, Kallol, et al. "High-Pressure High-Temperature Melting and Recrystallization of 3-D Printed and Annealed Nanolamellar Alloys." Submitted Summer 2024

Presenters

  • Andrew D Pope

    • University of Alabama in Birmingham

Authors

  • Andrew D Pope

    • University of Alabama in Birmingham