Mechanical properties of the CoCrFeNiMnVx high entropy alloys in temperature range 4.2–300 K

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

“…For instance, Chen et al reported that L1 2 particles could provide an obstacle for the mobile dislocations during compression in an Al 0.5 CoCrCuFeNi HEA [155]. Transmission electron microscopy (TEM) characterization revealed that L1 2 nanoparticles were present in the matrix for the samples tested at 500 and 600 • C. In another study [193], it has been reported that, in CoCrFeNiMnV x HEAs, sigma-phase particles and dendrite boundaries can provide a barrier to dislocation motion, resulting in serrations. Twinning, which occurs at cryogenic temperatures, is another mechanism that can lead to the serrated flow in HEAs by hindering dislocation motion at twin boundaries [8,9,122,123,159].…”

“…Furthermore, the strain rate at which a transition in the serration type occurred, i.e., Type-A to Type-A + Type-B transition increased with an increase in the temperature. Similar to conventional crystalline alloys, the serrated flow in HEAs can be affected by factors such as temperature and strain rate [152,153,155,180,193]. For example, Type-C serrations have been typically observed at relatively lower strain rates and higher temperatures, while the reverse is true for Type-A serrations [152,153,155,180].…”

“…For example, Type-C serrations have been typically observed at relatively lower strain rates and higher temperatures, while the reverse is true for Type-A serrations [152,153,155,180]. In an Al0.5CoCrCuFeNi HEA, for example, the transition from Types A to C serrations with increasing temperature was attributed to the increase in the migration Similar to conventional crystalline alloys, the serrated flow in HEAs can be affected by factors such as temperature and strain rate [152,153,155,180,193]. For example, Type-C serrations have been typically observed at relatively lower strain rates and higher temperatures, while the reverse is true for Type-A serrations [152,153,155,180].…”

Effect of carbon content and annealing on structure and hardness of CrFe2NiMnV0.25 high-entropy alloys processed by high-pressure torsion

“…Microstructural evolution of the fcc HEA was studied earlier [5,32] and it was found that the most significant plasticity mechanism at low homologous temperatures was gliding of full <110> dislocations on the primary {111} planes with part of the <110> dislocations splitting into 1/6<112> Shockley partials containing stacking faults. Hard precipitates in the fcc HEAs, such as particles of the σ-phase, act as strong barriers for dislocation motion so that most plasticity takes place in the matrix fcc phase [33]. The mechanisms of plasticity in fcc nanocrystalline materials are not fully understood at the present time but generally it is considered that grain boundary sliding is especially important at grain sizes below ~10-15 nm whereas for larger grains the motion of partial dislocations becomes dominant and this changes to the gliding of full dislocations when the grain size increases above ~100 nm [34].…”

Thermally activated deformation of nanocrystalline and coarse grained CoCrFeNiMn high entropy alloy in the temperature range 4.2–350 K

“…These properties are related to the multicomponent structure of the alloys and distorted crystal lattice due to presence of elements with different atomic radius. At present, the most prominent HEA is CoCrFeNiMn, which has a single fcc phase and high plasticity at all temperatures, including cryogenic ones [4][5][6][7]. The carriers of plasticity are reliably found in a wide range of temperatures [5,6].…”