CoCrFeNiMn High Entropy Alloy Research Articles

Wear Resistance of N-Doped CoCrFeNiMn High Entropy Alloy Coating on the Ti-6Al-4V Alloy

Wear Resistance of N-Doped CoCrFeNiMn High Entropy Alloy Coating on the Ti-6Al-4V Alloy

Investigating the Effects of Boron Nitride on Mechanical Properties of CoCrFeNiMn Composites

High‐entropy alloys (HEAs) are gaining attention for their exceptional properties but achieving precision and surface quality in powder metallurgy (PM) can be challenging. This study investigates the mechanical properties of CoCrFeNiMn HEAs produced through the flake powder metallurgy (FPM) technique and laser powder bed fusion (LPBF) preservative industrial, which established outstanding antiwear properties. To assess the enhancement of mechanical behavior and wear resistance by incorporating boron nitride (BN) into CoCrFeNiMn composites is fabricated via FPM. By incorporating BN into the composites, the mechanical behavior is significantly enhanced, leading to improved resistance against wear. Furthermore, the study delivers comprehensions into the serration behavior microstructure and shear localization in a high‐strain‐rate‐deformed CoCrFeMnNi entropy‐high alloy produces through metallurgy in powder. The serration behavior of the CoCrFeMnNi HEA is discussed concerning strain rate and temperature. Accordingly, the study employs the LPBF technique to fabricate the CoCrFeMnNi alloy from the prepared flakes. Microstructural characterization using scanning electron microscopy and X‐ray diffraction techniques to explore phase distribution, grain size, and possible segregation in the CoCrFeMnNi alloy produced through FPM‐LPBF is performed. In this particular investigation, a gradient microstructure is achieved through fusion in a laser‐powder bed of CoCrFeMnNi HEA onto highly deformed equal‐atomic HEA sheets. The resulting combination of partially recrystallized regions, exhibiting elevated yield strength, and fully recrystallized regions, demonstrates enhanced strain hardenability and elongation, and yields superior mechanical properties. The results obtained from the FPM‐LPBF CoCrFeMnNi alloy will be compared with those of conventionally processed CoCrFeMnNi to highlight the advantages and improvements achieved through the proposed method. The study findings reveal that the fundamental understanding of HEAs’ behavior under LPBF with FPM affords valuable insights into optimizing the processing parameters and achieving superior mechanical attributes.

Influence of twinning thickness on the mechanical properties of crystalline-amorphous dual-phase CoCrFeNiMn high entropy alloy

This study employs molecular dynamics simulation to investigate the influence of twin thickness on the mechanical properties and plastic deformation mechanisms for crystalline/amorphous dual-phase CoCrFeNiMn high-entropy alloy with varying amorphous layer thicknesses. The results revealed that for a minor amorphous layer thickness (d) of 1 nm, increasing the twin thickness (h) decreased average flow stress and peak stress within the models. It can be attributed to the fact that at smaller h, twin boundaries effectively hinder dislocation motion. However, as h increases, dislocation storage near twin boundaries and subsequent large-scale FCC→HCP phase transformation become more robust, reducing stress. On the other hand, when d thickness increases to 7 nm, stable average flow stress is observed due to thicker shear band formation during plastic deformation. Regardless of whether d was 1 nm or 7 nm, an increase in twin thickness augmented the likelihood of FCC→HCP phase transformation.

High creep resistance in amorphous/crystalline dual-phase nanostructured CoCrFeNiMn high entropy alloys

Amorphous/crystalline dual-phase metallic materials received great attention owing to their synergistic combination of strength and ductility. However, the mechanisms governing creep deformation in these dual-phase materials are largely elusive. In the present letter, the creep deformation of amorphous/nanocrystalline CoCrFeNiMn high-entropy alloy (HEA) films is investigated through nanoindentation creep testing. It is suggested that dual-phase HEAs exhibit reduced creep strain compared to their monophase counterparts, and even surpass the performance of coarse-grained variants. This behavior arises from diffusion processes within the amorphous phase and the capacity for nucleation/annihilate of dislocations at amorphous/nanocrystalline interfaces. Furthermore, it is proposed that the presence of glass shell significantly influences the creep behavior of dual-phase HEAs.

Effect of Mn element on shock response in CoCrFeNiMnx high entropy alloys

Abstract The effect of Mn element on shock response of CoCrFeNiMn x high entropy alloys (HEAs) are investigated using molecular dynamics simulations. Structural analysis shows that Mn-rich CoCrFeNiMn x HEA has a larger average atomic volume. The elastic properties of CoCrFeNiMn x HEAs under various hydrostatic pressures are studied, revealing that the elastic modulus decreases with increasing of Mn content. The shock thermodynamic parameters are quantitatively analyzed. The Mn-dependent shock Hugoniot relationship of CoCrFeNiMn x HEAs is obtained: U s = 1.25 + (5.21–0.011x)U p. At relatively high shock pressure, the increase in Mn content promotes the formation of clustered BCC structures and hinders the development of dislocations. In addition, more FCC structures in Mn-rich CoCrFeNiMn x HEAs transform into disordered structures during spallation. Spall strength decreases with increasing Mn content. This study can provide a reference for the design and application of CoCrFeNiMn HEAs under shock loading.

Comparative study of microstructure and mechanical properties of cold rolled and annealed CoCrFeNi-MEA and CoCrFeNiMn-HEA fabricated by laser energy deposition

Equi-atomic quaternary CoCrFeNi Medium-entropy alloy (MEA) and quinary CoCrFeNiMn high-entropy alloy (HEA) are fabricated by laser energy deposition, followed by 5-pass cold rolling to total reduction of 70 % and annealing at temperatures of 600–1000 °C for 1 h. CoCrFeNi-MEA is severely cracked while CoCrFeNiMn- HEA is slightly cracked after cold rolling. Hardness of as deposited and fully recrystallized (heat treating temperature at 800–1000 °C) CoCrFeNi-MEAs are slightly higher than those of CoCrFeNiMn- HEAs, due to the larger atomic size misfit and lattice strain in CoCrFeNi-MEA than in CoCrFeNiMn-HEA. However, the higher microhardness of CoCrFeNiMn-HEAas-rolled than CoCrFeNi-MEAas-rolled is associated with the higher strain state in CoCrFeNiMn-HEAas-rolled than in CoCrFeNi-MEAas-rolled. With the increase of heat-treating temperature, microhardness of CoCrFeNi-MEA increases first and then decreases due to the precipitation hardening effect of Cr-rich (B2) particles in CoCrFeNi-MEAR-600. Microhardness of CoCrFeNiMn-HEA decreases with the increase of annealing temperature because of the weaker precipitation hardening effect of MnNi phase (L10) and Cr-rich particles (BCC) after annealing at 600 ℃ and higher temperatures. CoCrFeNi-MEAR-700 is much harder than CoCrFeNiMn-HEAR-700 because CoCrFeNi-MEAR-700 is partially recrystallized and CoCrFeNiMn-HEAR-700 is fully recrystallized. Strength behavior of the two alloys is consistent with microhardness behavior. {100}<110> texture component is acquired in both CoCrFeNi-MEAas-rolled and CoCrFeNiMn-HEAas-rolled. <111>//ND texture is observed in both alloys after annealing at 600 ℃. Orientation of recrystallized grains is random in both alloys. Size of recrystallized grains in CoCrFeNiMn-HEA is slightly larger than those in CoCrFeNi-MEA since homologous temperature (T/Tm) of CoCrFeNiMn-HEA is slightly higher than that of CoCrFeNi-MEA.

Microstructure and mechanical properties of resistance spot welded dissimilar aluminum/steel joints fabricated using high entropy alloy as interlayer

To improve the welding quality of Al/steel joint during resistance spot welding (RSW) process, a CoCrFeNiMn high entropy alloy (HEA) sheet was employed to be an interlayer between aluminum alloy and high strength steel parent metal sheets. Through a series of comparative studies and analyses, the Al/steel spot welded joint obtained from the process with the HEA interlayer had a larger aluminum nugget diameter and thinner intermetallic compound (IMC) layer when compared to a conventional RSW process. When the thicknesses of two parent metal sheets were 1.0 mm or 1.5 mm, the aluminum nugget diameter of the Al/steel spot welded joint with the HEA interlayer were 4.904 mm and 5.962 mm, and respectively increases by 28.41% and 31.32% compared to a conventional RSW process. For the 1.5 mm of the thickness of the parent metal sheets, the HEA interlayer can make the layer thicknesses at the Al/steel faying interface decrease from 3.2 μm to 1.3 μm. Also, adding the HEA interlayer could induce more welding heat energy respectively by 30.74% and 30.34%, and significantly improve the lap-shear strength of the joint by 56.95% and 52.09% for two thicknesses of the parent metal sheets. Even increasing welding current of the process without HEA interlayer to make its calculated welding heat energy the same as that with HEA interlayer, the Al/steel joint obtained from the process with HEA interlayer still had a higher lap-shear strength. In addition, by seriously observing and analyzing the fracture surfaces obtained from processes with and without the HEA interlayer, it could be concluded that the HEA interlayer could improve the fracture mode of the Al/steel joint from interfacial fracture to button fracture, so the quality of the Al/steel joint could be improved. This work can supply an effective method to improve the dissimilar metals welding process.

Low cycle fatigue properties of CoCrFeNiMn high-entropy alloy with heterogeneous microstructure

Heterogeneous microstructure is a hot topic in materials science which facilitates tackling the dilemma of strength-ductility trade-off in engineering materials including high-entropy alloys. The present investigation was conducted on the impact of different microstructures including heterogeneous microstructure, constructed by thermomechanical treatment including cold rolling followed by annealing, on the monotonic and cyclic behavior of a CoCrFeNiMn high-entropy alloy. The tailored microstructure contained three features: non-recrystallized as a hard domain, ultrafine-recrystallized, and fine-recrystallized regions. A desirable combination of strength and ductility including UTS of ∼1.1 GPa together with an elongation of ∼15 % was achieved due to benefiting from hetero-deformation-induced hardening and activation of deformation twins in the fine recrystallized grains. Regarding low-cycle fatigue behavior, at the strain amplitude of 0.4 %, heterogeneous microstructure exhibits remarkable fatigue properties, including high maximum stress and extraordinary lifetime (more than 2 × 105). The compelling reasons for these desirable properties are triggering deformation twins in fine recrystallized grain, the absence of brittle sigma phase as a good location of crack initiation, and the non-recrystallized area as a hard domain for suppressing crack propagation. The results suggested that the heterogeneous microstructure has significant benefits during applying low strain amplitude, however, at high strain amplitude, grain refinement is not recommended, and coarse-grained microstructure provides better properties. The present investigation is a step forward to understand the significance of heterogeneous microstructures to improve fatigue properties of high- or medium-entropy alloys.

Effects of W element on the microstructure, wear and cavitation erosion behavior of CoCrFeNiMnWx high entropy alloy coatings by laser cladding

CoCrFeNiMnWx (x = 0, 0.5, 1, 1.5, 2) high entropy alloy (HEA) coatings were prepared on the surface of 304 stainless steel (304 SS) by laser cladding technology. The effects of W addition on the microstructure, microhardness, friction and wear properties, and cavitation erosion (CE) resistance of the coatings were thoroughly studied. The results show that the phase structure of the CoCrFeNiMnWx HEA coatings exhibits FCC structure, and the microstructure is typical dendrite (DR) and inter-dendrite (ID) morphology. With the increase of W content, the average grain size of CoCrFeNiMnWx HEA coatings gradually decreases. The microhardness of CoCrFeNiMnWx HEA coatings increases first and then decreases due to the brittle cracking caused by the excessive addition of W element. The wear resistance of CoCrFeNiMnW1 HEA coating is the highest, and its wear rate is much lower than that of CoCrFeNiMn HEA coating without W addition. The wear mechanism of CoCrFeNiMnWx HEA coatings is mainly adhesive wear, abrasive wear and oxidation wear, and the fatigue wear mechanism appears on CoCrFeNiMnW2 HEA coating. In addition, CoCrFeNiMnW1 HEA coating displays the highest CE resistance, and its mass loss after CE in 3.5 wt%Nacl solution is lower than that of CoCrFeNiMn HEA coating. The appropriate addition of W element can effectively improve the resistance to wear and CE of CoCrFeNiMnWx HEA coatings, showing a great potential in improving the service lifespan of overflow parts in marine environment.

Impact of copper and manganese on phase transformation, microstructural development and material strength in CoCrFeNi high-entropy alloys through mechanical alloying

CoCrFeNiX (X = Cu, Mn) equiatomic high-entropy alloys (HEAs) were prepared through mechanical alloying (MA) followed by sintering at moderate temperature. The prepared HEAs were subjected to X-ray diffraction and microscope techniques to evaluate their phase evolution, microstructure, and elemental composition. Alloyed CoCrFeNiCu powder consists of two face centered cubic (FCC) phases (FCC1 and FCC2), whereas, CoCrFeNiMn powder showed a major FCC phase with a minor body centered cubic (BCC) phase. After sintering, bulk CoCrFeNiMn alloy showed only a single solid solution FCC phase, and the bulk CoCrFeNiCu still contained dual FCC phases. The elemental composition analysis revealed that both HEAs are equiatomic in composition. The average microhardness of CoCrFeNiCu and CoCrFeNiMn HEAs was 85 ± 15 HV and 147 ± 20 HV, respectively. It was observed that the presence of Cu in CoCrFeNiCu reduces the hardness of the HEA due to segregation. This study demonstrates the influence of the fifth metal on the phase evolution, microstructure, and mechanical properties of the HEAs.

Microstructure evolution, wear and corrosion behavior of WC reinforced CoCrFeNiMn high-entropy alloy composite coatings by induction cladding

In this study, CoCrFeNiMn high entropy alloy (HEA) composite coatings reinforced with different WC particle contents were prepared by induction cladding technology for the first time. The effects of WC particle contents (0–70 wt%) on the microstructure, hardness, wear resistance and corrosion resistance of the coatings were analyzed. The results showed that the coatings prepared by induction cladding exhibited good metallurgical bonding with the substrate. The addition of WC particles led to grain refinement in the CoCrFeNiMn HEA together with second-phase strengthening and solid solution strengthening, improving the microhardness of the coatings. Compared to the average hardness value of 183 HV0.5 for the CoCrFeNiMn HEA coating, the composite coating with 60 wt% WC particle content exhibited the highest average hardness value of 679 HV0.5. The addition of WC particles significantly enhanced the wear resistance of the composite coating, with wear mechanisms including adhesive wear, abrasive wear, fatigue wear and oxidation wear. The composite coating with 60 wt% WC particle content demonstrated outstanding wear resistance, with a specific wear rate value of 0.491 × 10−6 mm3N−1 m−1, representing a reduction of approximately 670 times compared to the CoCrFeNiMn HEA coating. However, the addition of WC particles caused uneven potential distribution within the composite coatings, leading to galvanic corrosion. The WC particles and precipitated carbides increased the defects in the passive film, thus reducing the corrosion resistance of the composite coatings.

Reduced graphene oxide (rGO) reinforced CoCrFeNiMn high entropy alloy: Microstructure, mechanical properties, and corrosion behavior

The CoCrFeMnNi high entropy alloy (Cantor), and its variant incorporating 0.2 wt% reduced graphene oxide (rGO), denoted as Cantor + rGO, were successfully synthesized using mechanical alloying followed by spark plasma sintering. Comprehensive characterization utilizing FESEM, XRD, and TEM provided detailed insights into the microstructural features of the materials. The addition of rGO reduced crystallite size from 209 nm to 169 nm, promoted a uniform distribution of carbide phases of smaller size, and enhanced microhardness from 421.8 HV to 510 HV for Cantor and Cantor + rGO, respectively. The incorporation of rGO into the Cantor structure led to an increase in compressive yield strength (CYS) from 1100 MPa for Cantor to 1250 MPa for Cantor + rGO sample. A significant decrease in corrosion current density of samples from 6.1 ± 1.5 μA/cm2 for Cantor to 1.4 ± 0.9 μA/cm2 for Cantor + rGO was observed due to the addition of rGO reinforcement. Moreover, the pitting corrosion resistance was increased in rGO-reinforced Cantor, as revealed by cyclic polarization test. This research underscores the potential for utilizing rGO as a reinforcing agent to optimize the mechanical and corrosion resistance characteristics of HEAs, offering promising avenues for advanced materials in diverse applications.

Deformation mechanism and microstructure evolution during superplastic deformation of friction stir processed CoCrFeNiMn high entropy alloy

Since superplastic formation offers a significant advantage in preparing the complex structure parts of HEAs, the study of their superplastic behavior is extremely important. Using friction stir processing (FSP) with an improved convex hemispherical shape tool, this study reported for the first time an equiaxed ultrafine-grained CoCrFeNiMn HEA (489 nm) with a maximum elongation of 870% at 675 °C and 3 × 10−4 s−1. This superplastic property is much larger than ever reported in the CoCrFeNiMn HEA, which is even larger than that of the nano-sized CoCrFeNiMn HEA (10 nm) prepared by the high-pressure torsion. A high proportion of high angle grain boundaries and twin boundaries, a hard Cr-rich phase, and the sluggish diffusion effect of the CoCrFeNiMn HEA were primarily responsible for the exceptional superplasticity. Additionally, this study provides the first elucidation of the mechanism underlying Cr precipitation and Cr-rich phase growth, as well as the function of low-energy annealed twins during superplastic deformation. The diffusion of Cr along dislocations and grain boundaries facilitated grain boundary sliding as the predominant deformation mechanism. This study elucidates the superplastic deformation mechanism and microstructure evolution, thereby furnishing theoretical guidance for the practical implementation of superplastic forming of complex components of HEAs. Additionally, it presents an efficient method for fabricating such components.

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Plasma-Cladded CoCrFeNiMn Coatings on Compacted Graphite Iron

CoCrFeNiMn high-entropy alloy coatings were deposited on compacted graphite iron (CGI) by plasma transfer arc cladding to strengthen and improve the wear resistance (performance) of the surface. The effects of different heat treatment processes on the microstructure and mechanical properties of the CoCrFeNiMn coatings were investigated. Compared with the deposited coating, the single FCC phase in the heat-treated coatings was retained, the grain size of the columnar dendrites decreased, the spacing between the dendrites increased, and the Cr-rich precipitated phase in the grain boundary increased. The heat treatment process had a positive influence on the microhardness and wear resistance of the coatings. The microhardness of the coatings increased after heat treatment. After heat treatment at 660 °C for 90 min, the coating had the highest microhardness of 563 ± 6.9 HV0.2, and it had the best wear resistance.

Superior strength and ductility in a C-containing CoCrFeNiMn high-entropy alloy with heterogeneous microstructure

The present study is focused on the beneficial effects of adding few amounts of carbon (0.76 at. %) and adopting microstructure engineering by a simple thermomechanical treatment to form a heterogeneous microstructure in a CoCrFeNiMn high-entropy alloy. The results demonstrate that the addition of carbon results in significantly higher strength and improved thermal stability when compared to carbon-free alloy under identical conditions. In fact, the addition of carbon results in strengthening through the solute drag effect and solid solution strengthening. Thermodynamic predictions and XRD patterns indicate that carbon addition enhances the tendency of carbide precipitation in the alloy instead of forming an undesirable σ phase. The microstructural observation reveals that the deformed microstructure remains nearly stable during annealing at temperatures up to 750 °C and complete recrystallization occurs after annealing at 1000 °C, resulting in the formation of a fine-grained microstructure. Post-deformation annealing at 800 and 900 °C leads to the formation of heterogeneous microstructures comprising regions with high dislocation density grains alongside recrystallized fine-grained areas. The results suggest a superior synergy between strength and ductility in the annealed sample at 800 and 900 °C, exhibiting the ultimate-tensile strength of ∼1000 and ∼835 MPa. Additionally, these samples demonstrate decent uniform elongation values of ∼10 and 20%, respectively.

Parameters optimization for laser-cladding CoCrFeNiMn high-entropy alloy layer based on GRNN and NSGA-II

In order to improve the bonding strength of FeCoCrNiMn cladding layer, laser power, scanning speed and powder feeding rate were selected as the optimization variables; the aspect ratio, dilution rate and heat affected zone depth of the cladding layer were selected as the optimization indicators; a three-factor three-level full-factor experiment was designed; a nonlinear model of cladding parameters and cladding performance was established by generalized regression neural network algorithm (GRNN), while the error of prediction value and experimental results was less than 10%. A set of optimal Pareto frontiers were obtained by the Non-Dominance Ordering Genetic Algorithm (NSGA-II), and the optimal individuals were obtained based on the equal weights, and the optimal cladding parameters were as follows: laser power 2.33 kW, scanning speed 2.90 m/min, and powder feeding rate 12.46 g/min. The cladding layer prepared under the optimal parameters has a dense cross-section with no defects such as cracks and porosity. The joint optimization using the GRNN neural network and the NSGA-II genetic algorithm can obtain excellent results, and the relative error between the experimental and predicted values can be controlled within 10%. The application of optimized laser process parameters can significantly improve defects such as poor adhesion, cracks and porosity on the surface of the cladding layer, and also improve the surface hardness and wear resistance. The experimental results show that the wear rate of the cladding layer prepared by the optimized parameters is 3.21×10−5 mm3/N·m, which is 1.5 times higher than that of the cladding layer prepared by P=2.1 kW, V=3 m/min and C=9 g/min. The wear mechanism mainly includes abrasive wear, plastic deformation and oxidative wear.

Diffusion in ultra-fine-grained CoCrFeNiMn high entropy alloy processed by equal-channel angular pressing

Grain boundary diffusion in severely plastically deformed (SPD) CoCrFeMnNi high entropy alloy (HEA) has been studied by applying the tracer diffusion technique. After two passes of equal channel angular pressing (ECAP), three untra-fast diffusion paths in ECAP-processed CoCrFeMnNi HEA were distinguished, which were identified with twin boundaries, high-angle grain boundaries and porosity defects. The enhanced diffusivity is induced by a high strain localization in the vicinity of interfaces in a deformation-induced non-equilibrium state that is correlated with the pronounced deformation twinning due to the low stacking fault energy of the material.

Wear-induced microstructural evolution in CoCrNi-based high-entropy alloys at cryogenic temperature

Elucidating the tribological behaviors of CoCrNi-based high-entropy alloys (HEAs) at cryogenic temperatures is crucial for their practical application. This work uncovers the correlation between the wear-induced microstructural evolutions and tribological properties of single-phase CoCrFeNiMn HEA and heterogeneous CoCrFeNiAl HEA upon two contact conditions at 173 K. When CoCrFeNiMn HEA matches with GCr15 rather than Si3N4, low contact stress and high flash temperature suppress the inhomogeneous deformation initiated by martensitic transformation and in turn create a gradient nanograined tribo-layer activated by high-density dislocations and nano-scale deformation twins, which progressively accommodates the frictional strain and reduces wear by an order of magnitude. Instead, the tribological properties of the CoCrFeNiAl HEA sliding against Si3N4 are slightly superior to those sliding against GCr15, owing to the elevated contact stress and reduced flash temperature thicken the protective recrystallized nanocrystalline tribo-layer. Our findings offer guidance for optimizing the tribological properties of HEAs in cryogenic environments.

Effects of current density on the mechanical properties and microstructures of CoCrFeNiMn high-entropy alloy

Electrically assisted forming has been a reliable method for enhancing the formability of metal components for decades. This study investigates the mechanical properties and microstructures of an equiatomic CoCrFeNiMn high-entropy alloy (HEA) under electrically assisted tensile (EAT). The results indicate that the CoCrFeNiMn HEA exhibits lower flow stress and elongation under EAT compared to samples deformed at room temperature (RT). The sample's temperature increases with current density, and the primary factor influencing the HEA's mechanical properties during EAT is the Joule heating effect. A model about yield strength (YS) increment is established to predict the YS of the HEA under EAT at different temperatures. As the amount of Joule heating rises, the dislocation width increases, reducing the lattice friction stress and resulting in an exponential decay of YS. Increased Joule heating caused by current leads to a higher dynamic recovery rate, resulting in a reduced proliferation rate of geometrically necessary dislocations. However, the change in dislocation recovery coefficients is little affected by the current density in CoCrFeNiMn HEA when the dynamic recovery produced by the current is not sufficient to increase the fracture strain. Deformation twins (DTs) form during deformation at RT and 10 A/mm2. However, as the current density surpasses 20 A/mm2, the flow stress becomes insufficient to induce the formation of DTs, leading to a decrease in strain-hardening ability and elongation. This study provides an experimental and theoretical foundation for forming HEA components.

Steam oxidation properties of graphene reinforced bioinspired laminated CoCrFeNiMn high-entropy alloy matrix composites at 1000 ℃

Laminated CoCrFeNiMn high-entropy alloy (HEA) matrix composites reinforced with 1.0 wt% graphene nanoplatelets (GNPs) were fabricated by mechanical ball milling and flake powder metallurgy, and were isothermal oxidized at 1000 ℃ for 100 h. Vacuum hot-pressure sintering (VHPS) shows a distinct nacre structure with the microstructure composed of FCC matrix phase, Cr23C6, CrMn1.5O4 precipitated phases, numerous dislocations and twins. High-temperature oxidation tests showed that the composites had mass gains at 12 h intervals from 12 to 100 h respectively. The oxidation kinetic curve changes from a linear pattern in the early stages to an exponential pattern in the later stages, which demonstrates better long-term oxidation resistance. The anisotropy of the laminated structure results in excellent resistance to high-temperature steam oxidation in the vertical lamellar direction. Observation of the cross-section reveals that although Cr2O3 (inner layer) is present, (Mn, Cr)3O4 and Mn3O4 are the dominant oxides (outer layer). Elemental depletion zones for Mn and Cr exist in the region of the matrix near the oxide scales. The results show that the oxidation resistance of the laminated GNPs/CoCrFeNiMn composites is mainly influenced by the diffusion of Mn and Cr elements, the microstructure of the laminations and the internal oxidation.