Entropy-driven melting point depression in fcc HEAs

• Published in: Scripta materialia Vol. 208; no. C; p. 114336
• Main Authors: Kirk, Tanner, Vela, Brent, Mehalic, Seth, Youssef, Khaled, Arróyave, Raymundo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.02.2022; Elsevier
• Subjects: Alloy design; High entropy alloys; High temperature applications; Melting; High entropy alloys; High temperature applications; Melting; Alloy design
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2021.114336

[Display omitted] High Entropy Alloys (HEAs) are an increasingly dominant alloy design paradigm. The premise of entropic stabilization of single-phase alloys has motivated much of the research on HEAs. Chemical complexity may indeed help stabilize single alloy phases relative to other lower-entropy competing solid phases. Paradoxically, this complexity may de-stabilize these alloys against the liquid phase, potentially limiting the application space of HEAs at elevated temperatures. In this work, we carry out a comprehensive investigation of the phase stability in the fcc CoCrFeMnNiV-Al HEA space using a state of the art CALPHAD database. By using modern visualization techniques and statistical analysis we examine the trade-off between chemical complexity and stability against the liquid state and identify a potentially difficult to overcome barrier for development of high temperature alloys, at least within the conventional fcc HEA space. Limited experimental data seem to be consistent with this analysis.