Investigation of electronic and thermal properties of CoCrFe and CoCrFeNi high entropy alloys via extended tight-binding DFT computational method

Authors : Fatih Ahmet ÇELİK, Sefa KAZANÇ

Pages : 11-21

Doi:10.55525/tjst.1164010

View : 19 | Download : 8

Publication Date : 2023-03-29

Article Type : Research Paper

Abstract :In this study, CoCrFe and CoCrFeNi transition high entropy alloys insert ignore into journalissuearticles values(HEAs); are modelled by extended tight-binding density functional theory insert ignore into journalissuearticles values(DFT); method. Also, the geometric optimizations, band structures, density of states insert ignore into journalissuearticles values(DOS);, thermodynamic properties and phonon dispersion curves of alloys are investigated to give a detailed information. The results show that the covalent d–d bonding between Fe-Cr is occurred because of strong metallic Cr–Fe interactions. The entropy insert ignore into journalissuearticles values(S); value increases gradually with the addition of Ni element to the CoCrFe alloy. The heat capacity insert ignore into journalissuearticles values(Cv); increases due to the harmonic effect of the phonons in the range of 0-400 K and then, close to the classic limit at high temperatures with 0.82 J/mol.K and 0.94 J/mol.K for the CoCrFe and the CoCrFeNi. The alloy systems exhibit metallic properties because the DOS of the metals have a nonzero value at the Fermi energy level. Also, the addition of element Ni to the CoCrFe alloy system causes a decrease in phonon frequencies.
Keywords : Simulation and modelling, metals and alloys, high entropy alloys, DFT method