TY - JOUR

T1 - Strain-stabilized Al-containing high-entropy sublattice nitrides

AU - Kretschmer, Andreas

AU - Holec, David

AU - Yalamanchili, Kumar

AU - Rudigier, Helmut

AU - Hans, Marcus

AU - Schneider, Jochen Michael

AU - Mayrhofer, Paul Heinz

N1 - Publisher Copyright: © 2021 The Author(s)

PY - 2022/2/1

Y1 - 2022/2/1

N2 - The impact of configurational entropy, enthalpy, and strain energy on the phase stability of high-entropy materials has not yet been investigated quantitatively. We used ab-initio calculations to predict the driving force for decomposition of 126 equimolar Al-containing high-entropy sublattice nitrides (HESN), which are all metastable with respect to all corresponding equimolar lower-entropy nitride phases. The entropy stabilization of ≈−0.06 eV/at. at 1073 K is overruled by the 0.10-0.27 eV/at. enthalpy-governed driving force for decomposition. Stabilization is however predicted for 22 compositions due to the −0.01 to - 0.28 eV/at. strain energy contribution caused by large differences in equilibrium volume between the HESN and their decomposition products. The predicted stabilities are consistent with diffraction and tomography data of annealed nitride coatings. Hence, it is evident that only strain enables the stabilization of the here studied Al-containing HESN, while the entropic contribution is overruled by endothermic mixing.

AB - The impact of configurational entropy, enthalpy, and strain energy on the phase stability of high-entropy materials has not yet been investigated quantitatively. We used ab-initio calculations to predict the driving force for decomposition of 126 equimolar Al-containing high-entropy sublattice nitrides (HESN), which are all metastable with respect to all corresponding equimolar lower-entropy nitride phases. The entropy stabilization of ≈−0.06 eV/at. at 1073 K is overruled by the 0.10-0.27 eV/at. enthalpy-governed driving force for decomposition. Stabilization is however predicted for 22 compositions due to the −0.01 to - 0.28 eV/at. strain energy contribution caused by large differences in equilibrium volume between the HESN and their decomposition products. The predicted stabilities are consistent with diffraction and tomography data of annealed nitride coatings. Hence, it is evident that only strain enables the stabilization of the here studied Al-containing HESN, while the entropic contribution is overruled by endothermic mixing.

UR - http://www.scopus.com/inward/record.url?scp=85120401209&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2021.117483

DO - 10.1016/j.actamat.2021.117483

M3 - Article

VL - 224.2022

JO - Acta materialia

JF - Acta materialia

SN - 1359-6454

IS - 1 February

M1 - 117483

ER -