Entropy Landscaping of High‐Entropy Carbides. Issue 42 (2nd September 2021)

• Record Type: Journal Article
• Authors: Hossain, Mohammad Delower; Borman, Trent; Oses, Corey; Esters, Marco; Toher, Cormac; Feng, Lun; Kumar, Abinash; Fahrenholtz, William G.; Curtarolo, Stefano; Brenner, Donald; LeBeau, James M.; Maria, Jon‐Paul
• Is Part Of: Advanced materials. Volume 33:Issue 42(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-02
• Subjects: configurational entropy -- electronic and vibrational entropy -- free energy -- high‐entropy carbides -- thermodynamic stability -- valence electron concentration; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202102904
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: The entropy landscape of high‐entropy carbides can be used to understand and predict their structure, properties, and stability. Using first principles calculations, the individual and temperature‐dependent contributions of vibrational, electronic, and configurational entropies are analyzed, and compare them qualitatively to the enthalpies of mixing. As an experimental complement, high‐entropy carbide thin films are synthesized with high power impulse magnetron sputtering to assess structure and properties. All compositions can be stabilized in the single‐phase state despite finite positive, and in some cases substantial, enthalpies of mixing. Density functional theory calculations reveal that configurational entropy dominates the free energy landscape and compensates for the enthalpic penalty, whereas the vibrational and electronic entropies offer negligible contributions. The calculations predict that in many compositions, the single‐phase state becomes stable at extremely high temperatures (>3000 K). Consequently, rapid quenching rates are needed to preserve solubility at room temperature and facilitate physical characterization. Physical vapor deposition provides this experimental validation opportunity. The computation/experimental data set generated in this work identifies "valence electron concentration" as an effective descriptor to predict structural and thermodynamic properties of multicomponent carbides and educate new formulation selections. Abstract : High‐entropy carbides are designed based on valence electron concentration (VEC). VEC describes entropy, enthalpy, free energy, volume, and metastability of high entropy carbides such that a new composition thermodynamic property can be explained based on VEC.