The impact of chemical short-range order on the thermophysical properties of medium- and high-entropy alloys

Author(s)

Andreoli, Angelo F. ; Fantin, Andrea ; Kasatikov, Sergey ; Bacurau, Vinicius P. ; Widom, Michael ; Gargarella, Piter ; Mazzer, Eric M. ; Woodcock, Thomas G. ; Nielsch, Kornelius ; Coury, Francisco G.

• Document type: Journal article
• Source: MATERIALS & DESIGN; v. 238, p. 15-pg., 2024-02-06.

Abstract

The unusual behavior observed in the coefficient of thermal expansion and specific heat capacity of CrFeNi, CoCrNi, and CoCrFeNi medium/high-entropy alloys is commonly referred to as the K-state effect. It is shown to be independent of the Curie temperature, as demonstrated by temperature-dependent magnetic moment measurements. CoCrFeNi alloy is chosen for detailed characterization; potential reasons for the K-state effect such as texture, recrystallization, and second-phase precipitation are ruled out. An examination of the electronic structure indicates the formation of a pseudo-gap in the Density of States, which suggests a specific chemical interaction between Ni and Cr atoms upon alloying. Hybrid Monte Carlo/Molecular Dynamic (MC/MD) simulations indicate the presence of non-negligible chemical short-range order (CSRO). Local lattice distortions are shown to be negligible, although deviations around Cr and Ni elements from those expected in a fully disordered structure are experimentally observed by X-ray absorption spectroscopy. The determined bonding distances are in good agreement with MC/MD calculations. A mechanism is proposed to explain the anomalies and calorimetric experiments and their results are used to validate the mechanism. (AU)

• FAPESP's process: 22/12641-0 - Evaluation of ordering effect on the properties of Multicomponent CrCoNi Alloys
• Grantee: Vinícius Pereira Bacurau
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 21/12056-7 - Soft magnetic composites produced by additive manufacturing
• Grantee: Angelo Fernandes Andreoli
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• 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