Explore the possibility of forming fcc high entropy alloys in equal-atomic systems CoFeMnNiM and CoFeMnNiSmM

Abstract

YE Guo-xin ( ) ZHANG Li-kun ( ), CHEN Tuo ( ), ZHANG Wen-jun ( ), ZHENG Zhen-huan ( ) Li Qiang ( ), SHAO Yan-qun ( ), ZHOU Bai-yang ( ), WANG Chen ( ) Abstract: The multi-principal high-entropy alloys (HEAs) are promising new alloys. However, it is a challenge to screen out the suitable composition from the diverse combinations. Referring to the prototype AuCu3 with AB3-L12 structure, where it becomes a face-centered cubic (fcc) structure if element A and B are the same element, the site occupying tendencies of the elements and thermodynamic functions are predicted by using the sublattice model supported with first-principles total energy calculations. By considering the Gibbs energy of formation and the configurational entropy, the fcc HEAs in available literatures are examined, and the results of the quinary system with equal-atomic composition CoFeMnNiM and the hexbasic system with equal-atomic composition CoFeMnNiSmM are reported, respectively, where the element M is selected from the rest of the periodical table. When M =Cr, Zn, Ru, Rh, Pd, Re, Os, Ir, or Pt in the quinary systems CoFeMnNiM and when M =Ru, Pd, or Pt in the hexbasic systems CoFeMnNiSmM , respectively, the alloys are recommended to be potential fcc HEAs. The new approach opens a new way to mine the rich ores of HEAs.Traditional strategy for developing alloys is to select one or two elements as principal components and other minor elements incorporated for desired microstructure and properties, such as iron-, copper-, and aluminumbased alloys [1] . Recently, high-entropy alloy (HEA), as a new concept and promising metallic material, was reported by Yeh et al [2] . The practical alloy systems are composed of five or more principal elements in equimolar or near-equimolar ratios, with atomic percent 5% 35%. The high-entropy alloys form simple face-centered cubic (fcc) or body-centered cubic (bcc) solid solutions rather than intermetallic compounds because of large mixing entropies. Based on Boltzmann's

Single-phase high-entropy alloys – an overview

“…The probability of the formation of fcc single-phase HEAs in the systems MnFeCoNiM and MnFeCoNiSmM (M -an other metallic element) based on a thermodynamic sublattice model and first-principles calculations was examined in [95]. This approach can give an idea whether particular elements prefer to be equally distributed on the Wyckoff positions or have a tendency to occupy only certain sites.…”

Determination of the transition to the high entropy regime for alloys of refractory elements

“…Zhang and Zhou [37] determined necessary conditions on entropy of mixing, atomic size, and enthalpy of mixing needed to be in the high-entropy regime. More recently, Wang et al [38] studied the transformation from fcc to bcc based on atomic packing efficiency and lattice distortions and Zhang et al suggested how to downselect potential alloying additions to 4-and 5-element fcc-based HEA (CoFeMnNi + X and CoFeMnNiSm + X) based on first-principles calculations and site occupancy schemes [39].…”