Computational thermodynamics-guided alloy design and phase stability in CoCrFeMnNi-based medium-and high-entropy alloys: An experimental-theoretical study

Author(s)

Silva, David D. S. ; Bertoli, Gustavo ; Neto, Nelson D. Campos ; Schell, Norbert ; Clarke, Kester D. ; Kaufman, Michael J. ; Clarke, Amy J. ; Coury, Francisco G. ; Bolfarini, Claudemiro

• Document type: Journal article
• Source: SCRIPTA MATERIALIA; v. 252, p. 8-pg., 2024-07-11.

Abstract

A computational thermodynamics approach has been employed to design CoCrFeMnNi-based medium- and highentropy alloys (M/HEAs) with systematically varied compositions (Co((80-X)/2)Cr((80-X)/2)FeXMn10Ni10 with x = 30, 40, and 50 at.%) and phase stability. Since the formation of sigma phase, usually brittle and undesirable, is a common concern, when this class of alloys is subjected to elevated temperatures (600-1000 degrees C), predicting its formation becomes essential. Thus, its formation and the phase equilibria were studied using the CALPHAD method, and two empirical methods, namely, valence electron concentration (VEC) and paired sigma-forming element (PSFE). Isothermal aging treatments at 900-1100 degrees C for 20 h were performed, since CALPHAD and VEC/PSFE predictions diverged. Both prediction methods were compared with experimental characterization by a combination of scanning electron microscopy and high-energy synchrotron X-ray diffraction. The predictions from the VEC/PSFE and CALPHAD calculations (depending on the database used) were shown to be quite accurate. (AU)

• FAPESP's process: 22/02770-7 - Integrated Computational Materials Engineering ICME: applied to modeling, production, characterization and testing high entropy alloys
• Grantee: Francisco Gil Coury
• Support Opportunities: Research Grants - Initial Project
• FAPESP's process: 23/03385-2 - Multi-user equipment approved in grant 2022/02770-7: nanoindentation
• Grantee: Francisco Gil Coury
• Support Opportunities: Multi-user Equipment Program