CoCrFeMnNi High-entropy Alloy Research Articles

Chemical-element-distribution-mediated deformation partitioning and its control mechanical behavior in high-entropy alloys

• Effect of chemical heterogeneities on plasticity and strength is studied using atomic simulations in high-entropy alloys. • Elemental anisotropy/difference factor is proposed, and then used to evaluate the short range order and predict the HEA properties. • Elemental anisotropy factor for optimal high performance is accurately estimated by machine learning. • By a machine learning approach coupled with MD simulations, elemental anisotropy ranges from 2.9 to 3. The chemical element distributions always strongly affect the deformation mechanisms and mechanical properties of alloying materials. However, the detailed atomic origin still remains unknown in high-entropy alloys (HEAs) with a stable random solid solution. Here, considering the effect of elemental fluctuation distribution, the deformation behavior and mechanical response of the widely-studied equimolar random CoCrFeMnNi HEA are investigated by atomic simulations combined with machine learning and micro-pillar compression experiments. The elemental anisotropy factor is proposed, and then used to evaluate the chemical element distribution. The experimental and simulation results show that the local variations of chemical compositions exist and play a critical role in the deformation partitioning and mechanical properties. The high strength and good plasticity of HEAs are obtained via tuning the chemical element distributions, and the optimal elemental anisotropy factor ranges from 2.9 to 3 using machine learning. This trend can be attributed to the cooperative mechanisms depending on the local variational composition: massive partial dislocation multiplication at an initial stage of plastic deformation, and the inhibition of localized shear banding via the nucleation of deformation twinning at a later stage. Using the new insights gained here, it would be possible to create new metallic alloys with superior properties through thermal-mechanical treatment to tailoring the chemical element distribution.

Deconvolution-based peak profile analysis methods for characterization of CoCrFeMnNi high-entropy alloy

In this study, we compare several peak profile analysis methods for the investigation of the CoCrFeMnNi high-entropy alloy (HEA) after the plastic deformation. We show that conventional Williamson - Hall (cWH) approach poorly correlates with measured peak broadening and some corrections must be introduced to improve the analysis. The correction for elastic modulus for different crystallographic directions or application of modified Williamson Hall (mWH) and modified Warren - Averbach (mWA) methods significantly improve the correlation between the model and experimental data. Peak profile analysis shows that the dislocation density of the CoCrFeMnNi alloy subjected to axial compression increases with increase in strain and reaches plateau at a strain of 47.5%. At the same time, the crystallite size decreases, and dislocation structure becomes more disordered.

Synergistic enhancement in strength and ductility of nitrogen-alloyed CoCrFeMnNi high-entropy alloys via multi-pass friction stir processing

The dynamic microstructural evolution and tensile performances of CoCrFeMnNi high-entropy alloys (HEAs) with and without nitrogen alloying subjected to multi-pass friction stir processing (FSP) were comparatively investigated. Results showed that the strength and ductility of nitrogen-alloyed CoCrFeMnNi HEAs were synergistically enhanced by multi-pass FSP. Compared to free-nitrogen CoCrFeMnNi HEAs, the gains in the processed zone of the nitrogen-alloyed CoCrFeMnNi HEAs exhibited not only more refinement，but also a monotonic decrease in average gain size (AGS) with the increase in FSP pass. In addition, nitrogen-alloyed CoCrFeMnNi HEAs had higher fraction of low angle boundaries (LABs) than free-nitrogen CoCrFeMnNi HEAs after multi-pass FSP. The interaction between nitrogen atoms and LABs during multi-pass FSP was indirectly proved by the comparison of microstructural thermal-stability between two groups FSP HEAs. Meanwhile, the mechanism of synergistical enhancement in strength and ductility of nitrogen-alloyed CoCrFeMnNi HEAs was discussed.

Improving anti-corrosion properties of CoCrFeMnNi high entropy alloy by introducing Si into nonmetallic inclusions

The microstructures and composition at and around inclusions in casted CoCrFeMnNi alloy were studied. It was found that the Cr-depletion zone caused by the formation of MnO·Cr2O3 was responsible for the corrosive catastrophe of the alloy. Si was introduced in the alloy to modify the microstructure and composition of the inclusions. Instead of forming harmful MnO·Cr2O3, stable amorphous MnO-SiO2 was formed in the Si-added CoCrFeMnNi, eliminating the Cr-depletion zone. Consequently, the corrosion resistance of the Si-added CoCrFeMnNi was largely improved. The present work reveals a way of increasing corrosion resistance by modifying inclusions that disrupt the homogeneity of passive films. Data availability statementAll research data supporting this publication are directly available within this publication.

Phase Volume Fraction-Dependent Strengthening in a Nano-Laminated Dual-Phase High-Entropy Alloy.

A recently synthesized FCC/HCP nano-laminated dual-phase (NLDP) CoCrFeMnNi high entropy alloy (HEA) exhibits excellent strength–ductility synergy. However, the underlying strengthening mechanisms of such a novel material is far from being understood. In this work, large-scale atomistic simulations of in-plane tension of the NLDP HEA are carried out in order to explore the HCP phase volume fraction-dependent strengthening. It is found that the dual-phase (DP) structure can significantly enhance the strength of the material, and the strength shows apparent phase volume fraction dependence. The yield stress increases monotonously with the increase of phase volume fraction, resulting from the increased inhibition effect of interphase boundary (IPB) on the nucleation of partial dislocations in the FCC lamella. There exists a critical phase volume fraction, where the flow stress is the largest. The mechanisms for the volume fraction-dependent flow stress include volume fraction-dependent phase strengthening effect, volume fraction-dependent IPB strengthening effect, and volume fraction-dependent IPB softening effect, that is, IPB migration and dislocation nucleation from the dislocation–IPB reaction sites. This work can provide a fundamental understanding for the physical mechanisms of strengthening effects in face-centered cubic HEAs with a nanoscale NLDP structure.

The origin of jerky dislocation motion in high-entropy alloys

Dislocations in single-phase concentrated random alloys, including high-entropy alloys (HEAs), repeatedly encounter pinning during glide, resulting in jerky dislocation motion. While solute-dislocation interaction is well understood in conventional alloys, the origin of individual pinning points in concentrated random alloys is a matter of debate. In this work, we investigate the origin of dislocation pinning in the CoCrFeMnNi HEA. In-situ transmission electron microscopy studies reveal wavy dislocation lines and a jagged glide motion under external loading, even though no segregation or clustering is found around Shockley partial dislocations. Atomistic simulations reproduce the jerky dislocation motion and link the repeated pinning to local fluctuations in the Peierls friction. We demonstrate that the density of high local Peierls friction is proportional to the critical stress required for dislocation glide and the dislocation mobility.

Effect of cell wall on hydrogen response in CoCrFeMnNi high-entropy alloy additively manufactured by selective laser melting

In this work, microstructural and mechanical response to hydrogen were investigated for CoCrFeMnNi high-entropy alloy (HEA) additively manufactured by selective laser melting (SLM) with and without heat treatment. Microstructural characterization, thermal desorption analyses, and slow-strain-rate tests were conducted to study the hydrogen trapping behavior and the effects of hydrogen on the deformation and fracture mechanism. The results showed that cell walls with high-density dislocations and Mn segregation provided hydrogen trapping and increased the high hydrogen capacity. This caused hydrogen embrittlement, accompanied by hydrogen-assisted intergranular cracking in as-built CoCrFeMnNi HEA. A heat treatment at 900 ℃ reduced dislocation density of the walls and eliminated the Mn segregation. Interestingly, hydrogen-induced ductilization was enabled in the heat-treated-SLM HEA. This is attributed to an appropriate twinability and twinning strain which greatly suppressed intergranular cracking in the surface layer. Therefore, tuning twinability through the control of microstructure is critical for a transition from hydrogen embrittlement to ductilization for SLM-built HEA.

Recrystallization and grain growth behavior of variously deformed CoCrFeMnNi high-entropy alloys: microstructure characterization and modeling

The recrystallization and grain growth behavior of CoCrFeMnNi high-entropy alloys (HEAs) with different plastic deformations were studied. Differential scanning calorimetry (DSC) tests were novelly adopted to characterize the recrystallization process. Experimental results suggest that pre-deformation has great promotion on the recrystallization rate and degree. The recrystallized grain size decreases with increasing deformation due to increased potential nucleation sites. Severe deformation and low annealing temperature are helpful to refine annealed grains. A static recrystallization model for variously deformed HEAs was developed, in which the recrystallization rate was expressed as a function of strain and annealing temperature. An improved grain growth model was established, which takes the recrystallization process into consideration and declares that the annealed grain size decreases first and then increases. The recrystallization fraction and the annealed grain size of the HEAs with different deformations annealed at different temperatures can be predicted.

Compositional stability in medium and high-entropy alloys of CoCrFeMnNi system under ion irradiation

The equiatomic high-entropy alloy (HEA) CoCrFeMnNi not only has excellent mechanical properties but also good irradiation resistance. However, the mechanical properties of some equiatomic medium-entropy alloys (MEAs) are superior to those of CoCrFeMnNi HEA. In this study, the irradiation resistance and changes in composition due to irradiation in CoCrNi and CoCrFeNi MEAs and CoCrFeMnNi HEA are investigated. Thin film samples of the MEAs and HEA and Ni used for comparison were irradiated with up to 1.7 × 1019 ions/m2 of 2.4 MeV Cu ions at 673 and 873 K. The average damage in the observed area was 1 displacement per atom (dpa). No voids were observed in any of the MEA and HEA samples even after irradiation at 873 K; however, large voids were formed in Ni irradiated at 873 K. This indicates that the irradiation resistance of CoCrNi and CoCrFeNi MEAs and CoCrFeMnNi HEA was better than that of Ni. In addition, the formation of stacking fault tetrahedra (SFTs), a type of vacancy cluster, at 873 K was much more pronounced in CoCrNi and CoCrFeNi MEAs than in CoCrFeMnNi HEA. Therefore, the irradiation resistance of CoCrNi and CoCrFeNi MEAs is lower than that of CoCrFeMnNi HEA. Moreover, significant Cr segregation occurred in the CoCrNi and CoCrFeNi MEA samples irradiated at 873 K. In contrast, no segregation occurred in CoCrFeMnNi HEA. First-principles calculation results show that the formation rate of Cr-dumbbells is higher in CoCrNi and CoCrFeNi MEAs than in CoCrFeMnNi HEA, and that Cr interstitials are more stable in the MEAs. Therefore, Cr segregation is more likely to occur in the MEAs. Element segregation may affect the irradiation resistance of the alloys.

Tailoring microstructure with spatial heterogeneity in CoCrFeMnNi high-entropy alloy via laser surface relaxation

The face-centered cubic single-phase CoCrFeMnNi equi-atomic HEA has excellent mechanical properties in a wide temperature range, from cryogenic to room temperature. However, the low yield strength at room temperature limits its application as a structural material. Herein, we propose a novel heterostructuring method named laser surface relaxation (LSR) as a strategy to overcome the strength-ductility dilemma. Unlike conventional heterostructuring methods, the LSR method can freely tune the microstructure with spatial heterogeneity. The LSR-treated CoCrFeMnNi HEA exhibited exceptional mechanical properties with a synergetic strengthening effect.

Relation of phase fraction to superplastic behavior of multi-principal element alloy with a multi-phase structure

An Al0.3CoCrNi medium-entropy alloy was annealed in two conditions to differentiate the phase fraction of nano-scaled B2 and sigma precipitates in FCC microstructure, processed by high-pressure torsion, and subjected to a superplasticity test. The Al0.3CoCrNi with different microstructure exhibited distinct superplastic performance, with maximum elongation of 1900% and 1735% from tensile deformation at 1073 K at the strain rate at 5 × 10−3 s−1 and 10−2 s−1, respectively. The microstructural analysis revealed that the superplasticity is dominantly governed by the grain boundary sliding mechanism with the accommodation of intragranular dislocations. The Al0.3CoCrNi alloy, after superplastic deformation, consists of the mixture of FCC, B2, and sigma phases with different phase fractions. The comparison of this multi-phase structured alloy at two conditions and the sister alloy, Al0.5CoCrFeMnNi high-entropy alloy, suggests that increment of B2 and sigma phase fraction is beneficial to promote high-strain rate superplasticity by limiting the grain growth.

Ultrasonic and size effects on the rheological behavior of CoCrFeMnNi high-entropy alloy

Ultrasonic vibration (UV) is capable of improving material flowability and surface quality of products, thus the UV-assisted micro-forming process has become a fascinating technology for fabricating micro-parts. However, when the part is downscaled to the submillimeter level, the rheological behavior of the material during UV-assisted plastic deformation will be significantly affected by the ultrasonic and size effects, which are still not well understood. Meanwhile, the rheological behavior and microstructure evolution of advanced multi-component alloys under UV-assisted deformation are unclear. In this research, a set of UV-assisted micro-compression tests and characterization tests were carried out to investigate the role of grain size, geometrical dimension, and sound energy density on the rheological behavior and microstructure of CoCrFeMnNi high-entropy alloy (Cantor alloy). The results showed that Cantor alloy exhibits an unusual acoustic residual softening (ARS) phenomenon, which is related to the alleviation of severe lattice distortion effect and the increase of stacking fault energy during the UV. The value of ARS is not only related to the sound energy density but also affected by the grain size and geometrical dimension. Furthermore, mathematical models were developed to quantitatively characterize the ultrasonic softening (US) and ARS. The model evaluation showed that the proposed model can well predict the influence of grain size, geometrical dimension, and sound energy density on US and ARS. These findings provide a fundamental understanding for the UV-assisted micro-forming of Cantor alloy.

Exceptional strength-ductility combination of additively manufactured high-entropy alloy matrix composites reinforced with TiC nanoparticles at room and cryogenic temperatures

The cryogenic mechanical properties and deformation behaviour of additively manufactured (AM) medium/high-entropy alloys (MEA/HEA) and their composites are seldom studied. This work fills this gap by systematically studying the mechanical properties, deformation behaviour and strengthening mechanism of the additively manufactured CoCrFeMnNi high-entropy alloy (HEA) and 2 wt% TiC/CoCrFeMnNi composite (HEC) at room (293 K) and cryogenic (93 K) temperatures. The TiC nanoparticles promote the densification behaviour, and they are uniformly distributed around and in interior of the cellular substructures of the HEC sample. The tensile tests reveal that the strength and ductility can be simultaneously increased in both HEA and HEC samples when the temperature decreases from 293 K to 93 K. The TiC nanoparticles significantly promote a remarkable combination of strength and ductility in the HEC at both 293 K and 93 K, and the cryogenic tensile strength of HEC (1506 ± 6.6 MPa) is the highest value reported for AM-fabricated MEA/HEAs. For the HEA sample, the significant increase in strength and ductility is attributed to an additional hardening contribution induced by multiple twin systems at 93 K, which results in a steady and even increased strain hardening rate. When the temperature decreases from 293 K to 93 K, a remarkable yield strength increment (344.4 MP) is found in the HEC sample, which is significantly higher than that of HEA (229.0 MPa). The difference in the increase in yield strength between HEA and HEC sample is ascribed to the difference in dislocation strengthening and Orowan strengthening, which are related to the temperature-dependent thermal expansion coefficient and elastic modulus, respectively. However, the HEC sample has a smaller ductility increase (10.3%) than the HEA sample (26.4%), since no additional hardening mechanism is generated during the cryogenic deformation in the HEC sample. This research provides a new route to design materials with a good combination of strength and ductility for cryogenic applications.

Toward tunable microstructure and mechanical properties in additively manufactured CoCrFeMnNi high entropy alloy

Tailoring microstructure and mechanical properties of structural materials to meet application requirements is a long-standing challenge in materials science. Here we have studied the effects of laser energy density (LED) on the microstructure and mechanical properties of single-track CoCrFeMnNi high entropy alloy (HEA) samples fabricated by laser directed energy deposition (LDED). The results indicate that the molten pool size of the single-track HEA samples gradually increases with increasing LED. All of the samples possess a single face-centered cubic (FCC) solid solution structure. The microstructures of the single-track HEA samples are mainly composed of columnar and equiaxed grains, and as the LED increases, their grain size increases while the micro-hardness decreases. Additionally, the relationship among the processing parameters, cooling rate and grain size was investigated via combining the numerical simulation and experimental observations. This work provides mechanistic insights into establishing the processing-structure-property relationships in the additively manufactured HEAs and contributes to achieve LDED of tunable HEA parts with desired microstructure and mechanical performance.

First-principles study of hydrogen-vacancy interactions in CoCrFeMnNi high-entropy alloy

Vacancies can easily capture H atoms in metals, forming hydrogen-vacancy complexes/clusters. In this work, the hydrogen-vacancy interactions in CoCrFeMnNi high-entropy alloy (HEA) were studied with first-principles calculations based on the density functional theory (DFT). The special quasi-random structure (SQS) method was used to construct a chemically disordered HEA, and the effects of solute H atoms on the formation energy of monovacancy, the formation energy and binding energy of multi-vacancy cluster were calculated. It is found that an H atom prefers to occupy an octahedral interstitial site neighboring a vacancy and attracts the charge from the surrounding first-nearest neighbor atoms (e.g. Co, Ni, Fe or Mn atom, excluding Cr atom), weakening the stability of the atoms around the vacancy and reducing the vacancy formation energy in CoCrFeMnNi HEA. After introducing H atoms, the formation energies of both vacancy and vacancy cluster decrease in CoCrFeMnNi HEA, but they are still higher than those in pure Fe and Ni. In addition, the reduction of the binding energy of vacancies in CoCrFeMnNi HEA is much lower than that in pure Fe and Ni, and the binding energy of vacancies even increases in some cases. The results of the first-principles calculations indicate that the solute hydrogen atoms, although promoting vacancies, unfavorably combining vacancies into clusters to form micro-voids. This provides a good explanation for the good resistance to hydrogen embrittlement of CoCrFeMnNi HEA observed in experiments.

Enhancement of tensile properties applying phase separation with Cu addition in gas tungsten arc welds of CoCrFeMnNi high entropy alloys

This study investigates the gas tungsten arc weldability of the high-entropy alloy CoCrFeMnNi using CoCrFeMnNi and CuCrFeMnNi fillers. The CoCrFeMnNi-based weld had the same face-centered cubic (FCC) structure as the base metal, and the CuCrFeMnNi-based weld exhibited phase separation of the Cu-rich phase in addition to the FCC structure. Although the grain size of the CuCrFMnNi-based weld was similar to that of the CoCrFeMnNi-based weld, the Cu-rich phase formed in the CuCrFMnNi-based weld enhanced its tensile properties. This occurred because the dislocation movement and slip band in the weld metal were hindered by the formation of the Cu-rich phase.

Microstructure and Friction Properties of CoCrFeMnNiTix High-Entropy Alloy Coating by Laser Cladding.

To enhance the friction and wear properties of 40Cr steel’s surface, CoCrFeMnNi high-entropy alloy (HEA) coatings with various Ti contents were prepared using laser cladding. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to characterize the phase composition, microstructure, and chemical composition of the samples. The findings demonstrated that the CoCrFeMnNiTix HEA coatings formed a single FCC phase. Fe2Ti, Ni3Ti, and Co2Ti intermetallic compounds were discovered in the coatings when the molar ratio of Ti content was greater than 0.5. The EDS findings indicated that Cr and Co/Ni/Ti were primarily enriched in the dendrite and interdendrite, respectively. Ti addition can effectively enhance the coating’s mechanical properties. The hardness test findings showed that when the molar ratio of Ti was 0.75, the coating’s microhardness was 511 HV0.5, which was 1.9 times the hardness of the 40Cr (256 HV0.5) substrate and 1.46 times the hardness of the CrCrFeMnNi HEA coating (348 HV0.5). The friction and wear findings demonstrated that the addition of Ti can substantially reduce the coating’s friction coefficient and wear rate. The coating’s wear resistance was the best when the molar ratio of Ti was 0.75, the friction coefficient was 0.296, and the wear amount was 0.001 g. SEM and 3D morphology test results demonstrated that the coating’s wear mechanism changed from adhesive wear and abrasive wear to fatigue wear and abrasive wear with the increase in Ti content.

Beneficial effects of deep cryogenic treatment on mechanical properties of additively manufactured high entropy alloy: cyclic vs single cryogenic cooling

• Cyclic deep cryogenic treatment was utilized to homogenize the residual stress and tune the microstructure of a high entropy alloy fabricated by laser melting deposition, in order to improve its overall mechanical properties. • Cyclic deep cryogenic treatment can induce an increased compressive residual stress and introduce various types of reinforcing defect microstructures into a high entropy alloy, including dense dislocations, intersecting twins, transformed HCP phase and nanograins, thus effectively overcoming the strength-ductility trade-off. • Compared to single-step DCT, cyclic DCT can reduce the residual stress gradients in the LMD-built sample, relieving or removing the tensile residual stress at the top surface. • Transformation to HCP phase can occur during the cyclic DCT process due to the cyclic reverting of the thermal stress to a high level on each cryogenic cooling, which promotes twinning on secondary habit planes and more frequent faulting. Additively manufactured (AM) metallic materials commonly possess substantial tensile surface residual stress, which is detrimental to the load-bearing service behavior. Recently, we demonstrated that deep cryogenic treatment (DCT) is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy (HEA) samples fabricated by laser melting deposition (LMD), by introducing high compressive residual stress and deformation microstructures without destroying the AM shape. However, carrying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process, which are undesirable as the mechanical properties will not be homogeneous within the sample. In this work, we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated CoCrFeMnNi HEA, and improve tensile strength and ductility, compared with single-step DCT of the same cryogenic soaking duration. Under cyclic DCT, the thermal stress is re-elevated to a high value at each cryogenic cooling step, leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation, compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over time. The enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the DCT. The results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.

Structure and properties of the CrMnFeCoNi high-entropy alloy irradiated with a pulsed electron beam

According to the technology of wire-arc additive manufacturing a nonequiatomic composition CoCrFeMnNi high-entropy alloy (HEA) was obtained. Deformation curves of samples in tension are plotted and analyzed after the HEA fabrication by the methods of wire-arc additive manufacturing (initial state) and after the electron-beam processing (EBP). The EBP results in a decrease in the HEA's strength and plastic properties. Along with a pit character of the fracture a presence of micropores and microlayerings are identified. A study of the HEA's fracture surface after the EBP except for regions with a ductile fracture mechanism revealed regions with a band (lamellar) structure. The area with a band structure increases with a growth in the beam electron density from 25% at 10 J/cm2 to 65% at 30 J/cm2. A diameter of separation pits in fracture bands varies in the limits (0.1–0.2) μm, which is considerably less than those of the remaining part of the HEA sample. An average size of crystallization cells formed in the EBP depends on the energy density of electron beam and increases from 310 nm at 15 J/cm2 to 800 nm at 30 J/cm2. A non-monotonous change in the scalar dislocation density, reaching a maximum value of ∼5.5 · 1010 cm-2 at a distance of 25 μm from the irradiation surface is revealed. It is suggested that defects being formed in surface layers in the EBP may be one of the reasons for decreasing the values of HEA strength and plasticity.

Trimodal hierarchical structure in the carbonaceous hybrid (GNPs+CNTs) reinforced CoCrFeMnNi high entropy alloy to promote strength-ductility synergy

The concept of adding reinforcement phase to high entropy alloys (HEAs) is relatively new. Introducing the carbonaceous hybrid reinforcements (graphene nano plates (GNPs) and carbon nano tubes (CNTs)) into traditional metal matrix has initiated a cumulative attention as they show cost-effective and superior performance compared to individual ones. Herein, carbonaceous hybrid (GNPs + CNTs) reinforced CoCrFeMnNi (Cantor) high entropy alloy was fabricated using mechanical alloying (MA) and spark plasma sintering (SPS). Based on the XRD, XPS, Raman, FESEM and STEM results, carbonaceous reinforcements could dissolve in the Cantor matrix alloy and also promoted carbides formation, where more content of ones were represented as reinforcement phase. It was also revealed the fairly uniform dispersed carbon element in the Cantor-(0.2 wt%) GNPs + CNTs composite via three distinct morphologies as plate like, tube and structural shapes. The average grain size achieved for the Cantor alloy and Cantor-(0.2 wt%) GNPs + CNTs composite was 260 nm and 157 nm, respectively. The 0.2 wt% addition of GNPs + CNTs into the Cantor alloy resulted in the increase of the micro-hardness from 490 HV to 540 HV, compressive yield strength (CYS) from 1332 MPa to 1697 MPa with overcoming the strength and fracture strain trade-off effect. Dislocation strengthening was acting as main strengthening mechanism. In the Cantor-(0.2 wt%) GNPs + CNTs composite, the promotion of strength–ductility synergy was affected by trimodal hierarchical structure due to presence of nano sized carbonaceous hybrid reinforcements following by two-dimensional structure of graphene, sub-micron sized grains and nano sized areas such as twins, precipitates and grains. Besides, bridging and pulling-out of reinforcement phase in the fracture surfaces of composite were response for advanced performance. This study provided high entropy alloy playground, where carbonaceous hybrid reinforcements can lead to the formation of a trimodal hierarchical structure, resulting to novel property opportunities.