Atomic Interactions and Order–Disorder Transition in FCC-Type FeCoNiAl1−xTix High-Entropy Alloys

Abstract

Single-phase high-entropy alloys with compositionally disordered elemental arrangements have excellent strength, but show a serious embrittlement effect with increasing strength. Precipitation-hardened high-entropy alloys, such as those strengthened by L12-type ordered intermetallics, possess a superior synergy of strength and ductility. In this work, we employ first-principles calculations and thermodynamic simulations to explore the atomic interactions and order–disorder transitions in FeCoNiAl1−xTix high-entropy alloys. Our calculated results indicate that the atomic interactions depend on the atomic size of the alloy components. The thermodynamic stability behaviors of L12 binary intermetallics are quite diverse, while their atomic arrangements are short-range in FeCoNiAl1−xTix high-entropy alloys. Moreover, the order–disorder transition temperatures decrease with increasing Ti content in FeCoNiAl1−xTix high-entropy alloys, the characteristics of order–disorder transition from first-principles calculations are in line with experimental observations and CALPHAD simulations. The results of this work provide a technique strategy for proper control of the order–disorder transitions that can be used for further optimizing the microstructure characteristics as well as the mechanical properties of FeCoNiAl1−xTix high-entropy alloys.

Deformation Behavior and Processing Map of AlCoCrFeNiTi0.5 High-Entropy Alloy at High Temperature

“…Zhao et al [15,16] studied the microstructure evolution, hardness and wear resistance of HEMB-Ni 2 B composite coating via first principle methods; the results show that the synergistic effect between the superhardness of HEMB and the large plastic deformation ability of Ni 2 B can significantly improve the wear resistance of HEMB-Ni 2 B coatings, with a friction coefficient as low as 0.13. Similar investigations have been also reported in references [15][16][17][18][19][20][21][22][23]. Yu et al [17] demonstrated that the structure of Al x CoCrFeNi HEA transforms from a single FCC phase to an FCC + BCC dual phase with the increases in Al contents.…”

“…Zhang et al [19] found that the surface roughness is the smallest of CoCrFeNiAl X (x = 0, 0.6, 1) with a 0.6 wt% Al addition. Wu et al [20] reported that the transition temperature from order to disorder in FeCoNiAl 1−x Ti x decreases with the increase in Ti content. Zhang et al [22] showed that the average microhardness of the AlCoCrFeNiTi 0.5 HEA coating reached 989 HV, which was 32% higher than AlCoCrFeNi and reduced wear by 85%.…”