Effects of Cr/Ni ratio on physical properties of Cr-Mn-Fe-Co-Ni high-entropy alloys

Physical properties of ten single-phase FCC CrxMn20Fe20Co20Ni40-x high-entropy alloys (HEAs) were investigated for 0 = x = 26 at%. The lattice parameters of these alloys were nearly independent of composition while solidus temperatures increased linearly by similar to 30 K as x increased from 0 to 26 at.%. For x >= 10 at.%, the alloys are not ferromagnetic between 100 and 673 K and the temperature dependencies of their co-efficients of thermal expansion and elastic moduli are independent of composition. Magnetic transitions and associated magnetostriction were detected below similar to 200 K and similar to 440 K in Cr(5)Mn(20)Fe(20)Co(20)Ni35 and Mn20Fe20Co20Ni40, respectively. These composition and temperature dependencies could be qualitatively reproduced by ab initio simulations that took into account a ferrimagnetic. paramagnetic transition. Transmission electron microscopy revealed that plastic deformation occurs initially by the glide of perfect dislocations dissociated into Shockley partials on {111} planes. From their separations, the stacking fault energy (SFE) was determined, which decreases linearly from 69 to 23 mJ.m(-2) as x increases from 14 to 26 at.%. Ab initio simulations were performed to calculate stable and unstable SFEs and estimate the partial separation distances using the Peierls-Nabarro model. While the compositional trends were reasonably well reproduced, the calculated intrinsic SFEs were systematically lower than the experimental ones. Our ab initio simulations show that, individually, atomic relaxations, finite temperatures, and magnetism strongly increase the intrinsic SFE. If these factors can be simultaneously included in future computations, calculated SFEs will likely better match experimentally determined SFEs. (c) 2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Automated summary

The physical properties of ten single-phase FCC CrxMn20Fe20Co20Ni40-x high-entropy alloys were investigated. The lattice parameters of the alloys were nearly independent of composition, while the solidus temperatures increased linearly with increasing Cr content. The alloys did not exhibit ferromagnetism in a certain temperature range, and the temperature dependencies of their coefficients of thermal expansion and elastic moduli were independent of composition. Ab initio simulations qualitatively reproduced the magnetic transitions and magnetostriction observed in the alloys. The plastic deformation of the alloys was found to occur initially by the glide of perfect dislocations on {111} planes. The stacking fault energy (SFE) was determined and found to decrease with increasing Cr content. However, the calculated intrinsic SFEs were lower than the experimental values. The ab initio simulations showed that atomic relaxations, finite temperatures, and magnetism strongly influenced the intrinsic SFE.