Next Article in Journal
Degradation Mechanism of a Sauce-Glazed Ware of the Song Dynasty Salvaged out of the Water at Dalian Island Wharf: Part I—The Effect of the Surface-Attached Composite Coagula
Previous Article in Journal
Effect of Simulated Mastication on Structural Stability of Prosthetic Zirconia Material after Thermocycling Aging
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Materials
Volume 16
Issue 3
10.3390/ma16031178
materials-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

The Effect of Copper on the Microstructure, Wear and Corrosion Resistance of CoCrCuFeNi High-Entropy Alloys Manufactured by Powder Metallurgy

by
Samat Mukanov
,
Pavel Loginov
*,
Alexander Fedotov
,
Marina Bychkova
,
Maria Antonyuk
and
Evgeny Levashov
Department of Powder Metallurgy and Functional Coatings, National University of Science and Technology «MISIS», Leninskiy Prospekt 4, 119049 Moscow, Russia
*
Author to whom correspondence should be addressed.
Materials 2023, 16(3), 1178; https://doi.org/10.3390/ma16031178
Submission received: 15 December 2022 / Revised: 12 January 2023 / Accepted: 13 January 2023 / Published: 30 January 2023
(This article belongs to the Special Issue Tribological Behaviors of Metallic Materials and Their Surface Research)
Browse Figures
Review Reports Versions Notes

Abstract

:
This paper focuses on the microstructure, phase composition, mechanical, tribological and corrosion properties of high-entropy alloys (HEAs) in the CoCrCuFeNi system depending on copper content, which was varied from 0 to 20 at. % with an increment of 5%. CoCrCuFeNi alloys were manufactured by powder metallurgy methods: mechanical alloying and hot pressing of element mixtures. The solubility limit of copper in CoCrFeNi solid solution was found to be 9 at. %. Segregation of irregularly shaped copper grains sized 1–30 μm is observed at concentrations above this solubility limit. As copper concentration increases, the phase composition of CoCrCuFeNi alloys changes from the single phase based on FCC1 solid solution (Cu = 0–5 at. %) to the dual-phase FCC1 + FCC2 alloy (Cu = 10–20 at. %), where FCC1 is the main phase and FCC2 is the secondary copper-rich phase. Tribological tests have shown that doping the CoCrFeNi alloy with copper increased wear resistance by 23% due to solid solution hardening. As copper content rises above 20%, the content of the secondary FCC2 phase increases, while wear resistance and alloy hardness decline. An analysis of wear tracks and wear products has shown that abrasion of CoCrCuFeNi alloys occurs via the abrasive-oxidative wear mechanism. The corrosion tests of CoCrCuFeNi HEAs in 3.5% NaCl solution had demonstrated that doping the alloy with copper at low concentrations (5–10%) leads to decreasing of corrosion resistance, possibly due to the formation of undesirable oxide Cu2O along with protective Cr2O3. At high copper concentrations (15–20%) galvanic corrosion is suppressed due to coarsening of FCC2 grains and thus decreasing the specific contact surface area between the cathode (FCC2) and the anode (FCC1).

1. Introduction

Developing novel alloys simultaneously characterized by excellent mechanical, tribological, and corrosion properties is one of relevant challenges in materials science. There exist many approaches to solving this problem: macro- and micro-doping of alloys; formation of special types of the structure (duplex, ultrafine, nanocrystalline, etc.); incorporating reinforcing nanoparticles or their formation during consolidation or heat treatment of alloys; implementing the TWIP and TRIP effects to achieve a balance between strength and ductility, etc. These approaches have been successfully used over the past 20 years to design novel materials under the concept of high-entropy alloys (HEAs), which was proposed by Cantor et al. [1] and Yeh et al. [2] in 2004. This class of materials includes alloys consisting of at least five components with their concentrations ranging from 5 to 35 at. %. A distinctive feature of HEAs is that a thermodynamically stable substitutional solid solution with the initial fcc, bcc, or hcp lattice [3] is formed due to the high entropy of mixing (>1.5 R [4]). This approach allows us to design new alloys with excellent combination of strength, ductility, hardness and wear resistance [5,6]. The presence of a high concentration of uniformly distributed passive oxide-forming elements such as Cr ensures outstanding corrosion resistance [7]. These features of HEAs provide their superiority over traditional steels or iron-based alloys for multi-purpose materials [8,9,10].
CoCrFeNi alloys are common HEAs. These HEAs are promising to be used as materials for manufacturing press molds, components of magnetic systems, catalysts, etc. [11]. One of important features of most HEAs belonging to this family is their high wear resistance that equals or even exceeds that of commercial-grade engineering steels, and steel 304 L in particular [11].
Improvement of the known CoCrFeNi-based HEAs is performed in compliance with the strategy for designing alloys exhibiting an effect of solid solution and dispersion strengthening by doping with various elements [12,13,14]. Al, Mn, V, and Nb are the most common modifying agents for CoCrFeNi-based HEAs. Thus, Yang et al. [14] found that doping the CoCrFeNi alloy with Al results in rearrangement of the initial fcc crystal lattice into the non-ordered (A2) or ordered (B2) bcc structure, which is accompanied by an increase in hardness from 1.83 to 5.6 GPa. This effect was proved in refs. [11,15,16,17]. Joseph et al. [17] carried out comparative wear resistant tests of AlCoCrFeNi HEA, stainless steel (AISI 304), and Inconel 718 superalloy in a broad temperature range up to 900 °C. Hardness of the equiatomic AlFeCoNiCr alloy (630 HV) was approximately 2.5-fold higher than that of steel (245 HV) and 1.5-fold higher than that of nickel superalloy (425 HV). The presence of the bcc phase was found to significantly increase hardness and wear resistance, while simultaneously reducing ductility [18]. Zhang et al. [19] reported the results of a comparative study of the effect of V and Mn in CoCrFeNi HEA on mechanical and tribological properties. Doping with vanadium also resulted in significant alloy reinforcement and improved wear resistance threefold compared to that of the CoCrFeNiMn HEA due to precipitation of the σ-CrV solid phase. Wear resistance and tribological properties of CoCrFeNi-based HEAs can also be improved by doping them with ductile metals such as copper [20,21,22,23,24]. It seems to be a promising candidate for improving the CoCrFeNi-based HEA because its physical and chemical properties are similar to those of the matrix. Nevertheless, the available data on mechanical and tribological properties of CoCrCuFeNi-based HEAs are controversial and fail to provide an unambiguous answer to the question whether copper doping is beneficial. Verma et al. [20] studied the effect of doping with 5, 9, 13, 17, and 20 at. % Cu on the microstructure and wear resistance of the CoCrFeNi alloy obtained by arc remelting in an argon medium. The increased copper content resulted in grain size reduction. In alloys with Cu content >2 at. %, the secondary phase consisting of pure copper precipitates was observed in the interdendritic region along with the fcc solid-solution phase. As copper concentration increased, hardness of the alloy rose from 136 to 169 HV. Tribological tests of HEAs at 25 and 600 °C showed that doping with up to 20 at. % copper increased wear resistance by 26% and 48%, respectively. At elevated temperatures, there was a self-lubricating effect caused by formation of CuO oxide film. Contradictory data regarding the effect of copper were obtained in other studies [21,22,23]. Since copper has a positive enthalpy of mixing [24] with Fe-Co-Ni-Cr alloy elements (13; 6; 4; and 12 J/mol, respectively), copper atoms are segregated in the interdendritic space and/or at grain boundaries during crystallization. Therefore, such pure copper precipitates can adversely affect hardness, corrosion, and wear resistance of multicomponent alloys.
One of the possible ways to improve the mechanical, tribological properties and corrosion resistance of CoCrFeNi-based HEAs is to apply powder metallurgy techniques. Currently the most commonly used methods for their production (arc melting, casting, additive manufacturing and others) involve the formation of a liquid phase, resulting in inhomogeneity, dendritic segregation and formation of eutectic-type structures [25]. Mechanical alloying of powder mixtures followed by hot pressing or spark plasma sintering allows obtaining materials with fine structure and uniform distribution of the elements, despite the limitations or even complete absence of their mutual solubility. This study aimed to investigate the effect of copper on the microstructure, mechanical, tribological, and corrosion properties of CoCrCuxFeNi HEAs fabricated by powder metallurgy, which involved high-energy mechanical alloying of element mixtures followed by solid-phase hot pressing. This technology allows one to produce homogeneous poreless materials from single-phase supersaturated solid solutions. This fact makes these fine-grained alloys differ from cast coarse-grained alloys with a dendritic structure. This type of structure is undesirable if high-level mechanical properties, corrosion and wear resistance need to be achieved.

2. Materials and Methods

Carbonyl iron and nickel powders, cobalt and chromium powders obtained by reduction, and electrolytic copper powder were used in this study. The equiatomic CoCrCuFeNi alloy was chosen as the basic composition and was subsequently doped with 5, 10, 15, and 20 at. % copper. The samples are designated as CoCrCu0.25FeNi, CoCrCu0.5FeNi, CoCrCu0.75FeNi, and CoCrCuFeNi.
Powder mixtures were fabricated by high-energy mechanical alloying (MA) on an Activator-2 sl planetary ball mill (PBM) (OJSC Chemical Machine Building Plant, Novosibirsk, Russia) in the following mode: rotational speed of jars, 694 rpm; duration, 30 min; grinding bodies (steel balls)-to-powder weight ratio, 15:1. The jars were filled with argon to prevent powder oxidation during the treatment.
Cylinder-shaped compact samples 50 mm in diameter and 4 mm high were fabricated by vacuum hot pressing (HP) on a DSP-515 SA setup (Dr. Fritsch, Fellbach, Germany) at temperature of 950 °C, pressure of 35 MPa, and isobaric exposure of 3 min.
X-ray diffraction analysis (XRD) of powder mixtures and compact samples was carried out on an automated DRON 4-07 X-ray diffractometer using monochromatic Cu-Kα (for powders) and Co-Kα (for compact samples) radiation in the Bragg–Brentano geometry. The lattice constants were measured with a relative error ∆a/a = 10−4 nm. The microstructure and composition of HEAs were examined by scanning electron microscopy (SEM) on a S-3400N electron microscope (Hitachi, Tokyo, Japan). The fine structure was studied using a JEM-2100 transmission electron microscope (Jeol, Tokyo, Japan).
Tribological tests were carried out with a high-precision tribometer (CSM Instruments, Peseux, Switzerland) according to ASTM G 99-17 and DIN 50,324 standards using the “pin-on-disk” scheme upon reciprocating motion. Balls (diameter, 3 mm) made of sintered silicon nitride Si3N4 were used as counterbodies. Test loading was 2 N; linear speed was 5 cm/s. Wear track length was 6 mm for the total travel distance of 4000 cycles. Fractographic examination that involved measurements of the abrasive groove profile and diameter of the wear spot of the counterbody was carried out using a WYKO NT1100 optical profilometer (Veeco, Plainview, NY, USA) and an AXIOVERT CA25 inverted microscope (Karl Zeiss, Jena, Germany).
Hardness was measured on a Vickers HVS-50 hardness tester (Time Group Inc., Beijing, China) at a load of 10 N. The elastic modulus (E) was measured on a Nano-Hardness Tester (CSM Instruments, Peseux, Switzerland) using a Berkovich diamond indenter at a load of 8 mN. The corrosion resistance tests for HEAs were carried out in 3.5% NaCl solution in a three-electrode cell connected to a VoltaLab 50 potentiostat (Radiometer Analytical, Villeurbanne, France) at room temperature.

3. Results

3.1. Preparing Powder Mixtures of CoCrCuFeNi HEAs

One of the objectives of this study was to produce CoCrCuxFeNi HEAs having a homogeneous structure and characterized by complete mutual dissolution of the components. This is not always feasible in the Co-Cr-Cu-Fe-Ni system because of the low solubility of copper in Fe, Co, and Cr, as well as the presence of the eutectics in the corresponding phase diagram. As a result, most CoCrCuxFeNi cast alloys have a coarse dendritic structure with structural components varying significantly in terms of their chemical composition and mechanical properties (the primary crystals based on (Fe)CoNiCr solid solution and the copper-based eutectics) [26,27,28,29,30].
Single-phase CoCrCuxFeNi precursor powders were produced by MA to achieve uniform distribution of elements (Figure 1). The four-component CoCrFeNi powders were a solid solution having a fcc crystal lattice and lattice constant of 0.3583 nm (designated as FCC). Doping with copper at concentration of 5–20 at. % did not give rise to other phases. Peak positions in the XRD patterns of CoCrCuxFeNi powders (peaks shifted to smaller 2θ angles) suggested that copper dissolution in the matrix increased the lattice period to 0.3609 nm (at 20 at. % Cu content).
The homogeneous structure was formed via the known mechanisms of mechanical alloying when high-intensity plastic deformation and friction welding of ductile metallic components took place [30,31].
The CoCrCuFeNi powder mixtures subjected to long-term treatment in the PBM were characterized by uniform distribution of elements (Figure 2).

3.2. The Structure of CoCrCuFeNi Compact Samples

Compact samples were prepared from MA powder mixtures characterized by different copper contents. Figure 3 shows the characteristic microstructures of CoCrCuFeNi HEAs with copper content of 0, 5, 10, 15, and 20 at. %. The basic CoCrFeNi alloy had a homogeneous structure, which indicates that the alloy contained a single phase. A single-phase structure was also observed when the alloy was doped with 5 at. % Cu, which indicated that copper was completely dissolved in the fcc solid solution. As copper content was increased to 10 at. % and 20 at. %, isostructural Cu-rich clusters were precipitated (their content being proportional to copper concentration).
The chemical composition of the respective structural component was studied by energy-dispersive X-ray spectroscopy (EDX) in order to assess the solubility limit of copper in the matrix phase. The samples doped with 10–20% copper were characterized by an identical copper content in this phase (9 at. %). The constant chemical composition of the matrix after doping with ≥10 at. % Cu presumably indicates that the solubility limit has been reached. These results agree with the data reported by Shkodich et al. [32].
Figure 4 shows the XRD patterns of hot-pressed CoCrCuxFeNi samples indicating that the basic CoCrFeNi alloy contained only the fcc solid solution with lattice constant a = 0.35752 nm (hereinafter FCC1). This fact demonstrates that phase transformations did not occur as powder mixtures were heated. In accordance with the views on copper solubility in the fcc lattice, phase segregation related to the positive enthalpy of mixing for the elements of the CoCrFeNi alloy [24,33,34] is observed at Cu contents >2 at. % [21]. However, the experimental data indicate that mechanical alloying and hot pressing increased the solubility limit of copper to 9 at. %. In particular, when doping the alloy with 5 at. % Cu, copper was completely dissolved in the fcc matrix solid solution, thus slightly increasing the lattice period (a = 0.35753 nm). XRD peak splitting was observed as copper content was increased above 10 at. %. It indicates that the secondary phase, hereinafter FCC2, was precipitated (lattice constants a = 0.36325 nm, 0.36111 nm and 0.35963 nm) for the CoCrCu0.5FeNi, CoCrCu0.75FeNi, and CoCrCuFeNi samples, respectively, being consistent with the literature data [35,36,37]. The intensity of XRD lines corresponding to the secondary FCC2 phase rose with increasing copper content in the HEA. The content of the FCC2 phase in the equiatomic CoCrCuFeNi alloy reached 15 wt.%. The average chemical composition of the FCC2 phase was identified by EDX: Cu, 90 at. %; Ni, 8 at. %; Fe, Co, and Cr, 2 at. % each.
The main reason for the formation of the FCC2 phase is extremely low mutual solubility of Cu with Co, Cr and Fe. Application of high energy processes, such as MA, for powder production allows us to obtain a solid solution with higher Cu concentration than is thermodynamically permissible. Thus, equiatomic MA powder mixture CoCrCuFeNi, obtained in our work, initially consists of a metastable phase, which is exposed to diffusion activated spinodal decomposition at hot pressing. The higher the amount of Cu is in CoCrCuxFeNi alloys, the higher is the concentration of FCC2 phase forms in the alloy.

3.3. Tribological and Physicomechanical Properties

Table 1 summarizes the results of tribological tests of the fabricated HEA samples with different Cu contents. Doping with copper in the specified range of concentrations and segregation of the secondary phase FCC2 did not noticeably change the coefficient of friction (Figure 5a). During the initial running-in of the friction couple at 250–360 cycles, the coefficient of friction decreased to 0.4 and subsequently increased to 0.7. The equiatomic CoCrCuFeNi alloy was characterized by a longer running-in period.
The wear track profiles of the CoCrCuFeNi alloy are shown in Figure 5b. One can see that doping with copper noticeably increased the wear resistance of CoCrFeNi (Table 1). There was an extremal dependence of reduced wear on copper concentration with a minimum at 5 at. % of Cu. Wear resistance of the CoCrCu0.25FeNi alloy increased due to solid solution hardening caused by crystal lattice distortion of the (Fe)Co,Ni,Cr solid solution. The CoCrCu0.5FeNi alloy was also characterized by high wear resistance. In this case, wear resistance was affected by two competing processes: improvement of mechanical properties of the solid solution FCC1 due to copper saturation up to the solubility limit and segregation of the copper-based phase FCC2 characterized by low hardness. The first process was probably predominant due to the low content of the secondary phase FCC2 (5 wt.%). Wear resistance of HEA declined with increasing copper concentration. The highest values of reduced wear were observed for the CoCrCu0.75FeNi and CoCrCuFeNi alloys (8.88 and 10.54 × 10−5·mm3/N·m, respectively), which was probably caused by increasing concentration of the soft FCC2 phase.
Figure 6 shows the results of studying the effect of copper concentration on hardness, elastic modulus, and wear resistance of HEAs. One can see that hardness values are correlated rather tightly with wear resistance. The function showing the dependence of the hardness of the CoCrCuxFeNi HEA on copper concentration has a maximum at 10 at. % (374 HV). The increased hardness in the concentration range of 0–10 at. % was associated with solid-solution hardening of the main FCC1 phase by copper. The maximum mechanical properties (hardness and elastic modulus) of the FCC1 phase were attained at copper concentrations higher than its solubility limit (9 at. %). The concentration of Cu-rich FCC2 phase in CoCrCu0.75FeNi and CoCrCuFeNi alloys increases, which is detrimental for hardness and wear resistance.
Figure 7 shows the SEM images of the wear tracks after the tribological tests. Grooves oriented along the direction of counterbody motion and showing signs of abrasive wear of the friction couple were detected on all the samples in the tribocontact zone (Figure 5 and Figure 7). In all the HEAs, the wear track surface was characterized by high content of regions with dark BSE contrast. EDX of these areas (Figure 8) shows the high oxygen concentration in the dark regions of abrasive grooves, which may be indicative of oxidation processes and, therefore, predominance of the oxidative wear mechanism. The partial formation of the oxide layer as a result of frictional heating is associated with the fact that Fe, Ni, Cr, and Cu are prone to forming rapidly growing oxides.
The cracks in the oxidized areas of wear tracks and partial delamination of the tribolayer are possibly related to the fact that the oxides formed during tests are more brittle and degrade more easily under the applied testing load. The difference in the coefficient of thermal expansion [34] compared to that of the initial FCC solid solution can be an additional factor contributing to delamination of the oxidized region. After local delamination of the oxidized regions of the wear tracks, the metal surface in the tribocontact zone can be reoxidized [38], which temporarily raises the coefficient of friction, thus increasing the wear of the material [14].
A detailed study of the wear products was performed by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDXS). The tribolayer consisted of a combination of highly dispersed particles with a cloudy shape and an amorphous structure (Figure 9). No selective oxidation of any component of the CoCrCuFeNi alloy was observed during the tribolayer formation. EDXS revealed that the tribolayer also contained 5 at. % silicon, which had initially been a component of the counterbody. Silicon was uniformly distributed in the tribolayer particles along with HEA components and oxygen (Figure 9). Since no Si3N4 phase grains have been detected among the wear products, one can infer that chemical interaction between the CoCrCuFeNi HEA and the counterbody material takes place during tribological tests, followed by silicon dissolution.

3.4. Corrosion Resistance of the HEA (Corrosion Analysis)

Figure 10 shows the polarization curves of CoCrCuxFeNi compact samples in 3.5% NaCl solution. The corrosion potential (E) and corrosion current density (I) were determined using the Tafel extrapolation method. The CoCrFeNi alloy exhibited high corrosion resistance, which can be seen from the low corrosion current I (0.4 mA·cm−2). The shape of the polarization curve at high E values indicates that the alloy was resistant to pitting corrosion due to formation of a stable passivating film based on Cr2O3 chromium oxide [36]. Doping the HEA with copper reduced the corrosion resistance in the case when this element was completely dissolved in the FCC solid solution matrix. This is indicated by the maximum corrosion current density (I = 3.38 mA·cm−2), which was directly proportional to the corrosion rate according to the Faraday’s law [39]. In this case, the undesirable oxide Cu2O deteriorating the protective properties of the passivation layer was formed on the sample surface along with Cr2O3 [40].
At 10–20 at. % copper concentration, the corrosion current density decreased monotonically from 2.24 to 0.4 mA·cm−2, being indicative of increasing corrosion resistance. A typical feature of the structure of the resulting HEAs was that it contained the secondary Cu-based phase. The heterogenous structure ensured conditions for galvanic corrosion between the structural components acting as a cathode (FCC2) and an anode (FCC) [41]. The FCC2 grains became coarser as copper concentration increased, thus reducing the specific contact surface area between the cathode and the anode and increasing corrosion resistance.

4. Conclusions

  • Compact samples of CoCrCuxFeNi HEA with copper content ranging from 0 to 20 at. % were fabricated using the powder metallurgy technology that combined high-energy mechanical alloying and hot pressing. A single-phase solid solution was formed at copper concentrations up to 5 at. %, while at copper concentrations of 10–20 at. %, the structure was dual-phase. The excess phase having a fcc lattice precipitated during hot pressing consisted of 90 at. % copper and caused disordering of the HEA.
  • The CoCrCu0.25FeNi alloy exhibited the maximum wear resistance upon friction in a couple with a counterbody made of sintered Si3N4. Doping with copper reduced the specific wear by 23% (from 6.68 to 5.17 10−5·mm3/N·m). The increase in wear resistance was attributed to solid solution hardening caused by distortion of the crystal lattice of the (Fe)Co,Ni,Cr solid solution. Wear resistance declined with increasing copper concentration due to segregation of the excess FCC2 phase and decreasing hardness.
  • Wear of the resulting CoCrCuxFeNi HEAs occurred via the abrasive-oxidation mechanism. The wear products were amorphous particles consisting of the alloy components with uniformly distributed oxygen and silicon elements.
  • The tests of the CoCrCuxFeNi HEAs in 3.5% NaCl solution revealed that formation of the duplex structure FCC1 + FCC2 had a beneficial effect on corrosion resistance compared to the single-phase HEA with composition CoCrCu0.25FeNi.

Author Contributions

Investigation, writing—review and editing, visualization: S.M.; conceptualization, funding acquisition, investigation: P.L.; methodology, investigation: A.F.; investigation, formal analysis: M.B.; investigation, formal analysis: M.A.; conceptualization, supervision: E.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Russian Science Foundation, grant number “22-79-10144”.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. Some data can be made available upon request.

Acknowledgments

This work was carried out with financial support from the Russian Science Foundation (Project No. 22-79-10144). The authors gratefully thank M.I. Petrzhik, the Head of the Testing laboratory for functional surfaces NUST MISIS, for his assistance in studying the mechanical properties.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Cantor, B.; Chang, I.T.H.; Knight, P.; Vincent, A.J.B. Microstructural development in equiatomic multicomponent alloys. Mater. Sci. Eng. A. 2004, 375–377, 213–218. [Google Scholar] [CrossRef]
  2. Yeh, J.W.; Chen, S.K.; Lin, S.J.; Gan, J.Y.; Chin, T.S.; Shun, T.T.; Tsau, C.H.; Chang, S.Y. Nanostructured High-Entropy Alloys with Multiple Principal Elements: Novel Alloy Design Concepts and Outcomes. Adv. Eng. Mater. 2004, 5, 299–303. [Google Scholar] [CrossRef]
  3. Rogachev, A.S. Structure, stability, and properties of high-entropy alloys. Phys. Met. Metallogr. 2020, 121, 733–764. [Google Scholar] [CrossRef]
  4. Murty, B.S.; Yeh, J.W.; Ranganathan, S. High Entropy Alloys; Butterworth-Heinemann: Oxford, UK, 2014; p. 218. [Google Scholar] [CrossRef]
  5. Gali, A.; George, E.P. Tensile properties of high- and medium-entropy alloys. Intermetallics 2013, 39, 74–78. [Google Scholar] [CrossRef] [Green Version]
  6. Tong, C.J.; Chen, M.R.; Yeh, J.W.; Lin, S.J.; Chen, S.K.; Shun, T.T.; Chang, S.Y. Mechanical performance of the AlxCoCrCuFeNi high-entropy alloy system with multiprincipal elements. Metall. Mater. Trans. A 2005, 36, 1263–1271. [Google Scholar] [CrossRef]
  7. Kuptsov, K.A.; Antonyuk, M.N.; Sheveyko, A.N.; Bondarev, A.V.; Ignatov, S.G.; Slukin, P.V.; Dwivedi, P.; Fraile, A.; Polcar, T.; Shtansky, D.V. High-entropy Fe-Cr-Ni-Co-(Cu) coatings produced by vacuum electro-spark deposition for marine and coastal applications. Surf. Coat. Technol. 2023, 453, 129136. [Google Scholar] [CrossRef]
  8. Ye, Y.F.; Wang, Q.; Lu, J.; Liu, C.T.; Yang, Y. High-entropy alloy: Challenges and prospects. Mater. Today 2016, 19, 349–362. [Google Scholar] [CrossRef]
  9. Soto, A.O.; Salgado, A.S.; Niño, E.B. Thermodynamic analysis of high entropy alloys and their mechanical behavior in high and low-temperature conditions with a microstructural approach–A review. Intermetallics 2020, 124, 106850. [Google Scholar] [CrossRef]
  10. Ali, N.; Zhang, L.; Liu, D.; Zhou, H.; Sanaullah, K.; Zhang, C.; Chu, J.; Nian, Y.; Cheng, J. Strengthening mechanisms in high entropy alloys: A review. Mater. Today Commun. 2022, 33, 104686. [Google Scholar] [CrossRef]
  11. Tung, C.-C.; Yehv, J.-W.; Shun, T.-T.; Chen, S.-K.; Huang, Y.-S.; Chen, H.-C. On the elemental effect of AlCoCrCuFeNi high-entropy alloy system. Mater. Lett. 2007, 61, 1–5. [Google Scholar] [CrossRef]
  12. Liu, W.H.; He, J.Y.; Huang, H.L.; Wang, H.; Lu, Z.P.; Liu, C.T. Effects of Nb additions on the microstructure and mechanical property of CoCrFeNi high-entropy alloys. Intermetallics 2015, 60, 1–8. [Google Scholar] [CrossRef]
  13. Yu, Y.; He, F.; Qiao, Z.; Wang, Z.; Liu, W.; Yang, J. Effects of temperature and microstructure on the triblogical properties of CoCrFeNiNbx eutectic high entropy alloys. J. Alloys Compd. 2019, 775, 1376–1385. [Google Scholar] [CrossRef]
  14. Yang, T.; Xia, S.; Liu, S.; Wang, C.; Liu, S.; Zhang, Y.; Xue, J.; Yan, S.; Wang, Y. Effects of AL addition on microstructure and mechanical properties of AlxCoCrFeNi High-entropy alloy. Mater. Sci. Eng. A 2015, 648, 15–22. [Google Scholar] [CrossRef]
  15. Wang, W.R.; Wang, W.L.; Wang, S.C.; Tsai, Y.C.; Lai, C.H.; Yeh, J.W. Effects of Al addition on the microstructure and mechanical property of AlxCoCrFeNi high-entropy alloys. Intermetallics 2012, 26, 44–51. [Google Scholar] [CrossRef]
  16. Chou, H.P.; Chang, Y.S.; Chen, S.K.; Yeh, J.W. Microstructure, thermophysical and electrical properties in AlxCoCrFeNi (0 ≤ x ≤ 2) high-entropy alloys. Mater. Sci. Eng. B 2009, 163, 184–189. [Google Scholar] [CrossRef]
  17. Joseph, J.; Haghdadi, N.; Shamlaye, K.; Hodgson, P.; Barnett, M.; Fabijanic, D. The sliding wear behaviour of CoCrFeMnNi and AlxCoCrFeNi high entropy alloys at elevated temperatures. Wear 2019, 428–429, 32–44. [Google Scholar] [CrossRef]
  18. Tsai, C.W.; Tsai, M.H.; Yeh, J.W.; Yang, C.C. Effect of temperature on mechanical properties of Al0.5CoCrCuFeNi wrought alloy. J. Alloys Compd. 2010, 490, 160–165. [Google Scholar] [CrossRef]
  19. Zhang, M.; Zhang, X.; Niu, M.; Jiang, Z.; Chen, H.; Sun, Y. High-temperature tribological behavior of CoCrFeNiV high-entropy alloys: A parallel comparison with CoCrFeNiMn high-entropy alloys. Tribol. Int. 2022, 174, 107736. [Google Scholar] [CrossRef]
  20. Verma, A.; Tarate, P.; Abhyankar, A.C.; Mohape, M.R.; Gowtam, D.S.; Deshmukh, V.P.; Shanmugasundaram, T. High temperature wear in CoCrFeNiCux high entropy alloys: The role of Cu. Scr. Mater. 2019, 161, 28–31. [Google Scholar] [CrossRef]
  21. Huang, L.; Wang, X.; Huang, B.; Zhao, X.; Chen, H.; Wang, C. Effect of Cu segregation on the phase transformation and properties of AlCrFeNiTiCux high-entropy alloys. Intermetallics 2022, 14, 107397. [Google Scholar] [CrossRef]
  22. Cai, Y.; Chen, Y.; Luo, Z.; Gao, F.; Li, L. Manufacturing of FeCoCrNiCux medium-entropy alloy coating using laser cladding technology. Mater. Des. 2017, 133, 91–108. [Google Scholar] [CrossRef]
  23. Hsu, Y.J.; Chiang, W.C.; Wu, J.K. Corrosion behavior of FeCoNiCrCux high-entropy alloys in 3.5% sodium chloride solution. Mater. Chem. Phys. 2005, 92, 112–117. [Google Scholar] [CrossRef]
  24. Takeuchi, A.; Inoue, A. Classification of Bulk Metallic Glasses by Atomic Size Difference, Heat of Mixing and Period of Constituent Elements and Its Application to Characterization of the Main Alloying Element. Mater. Trans. 2005, 46, 2817–2829. [Google Scholar] [CrossRef] [Green Version]
  25. Liu, J.; An, X.; Zhang, J.; Kong, Q.; Li, Q.; Wang, H.; Yao, W.; Wang, Q. Microstructure, mechanical and corrosion properties of Co- and Cu-free AlxCrFeNi2.5Mo1-x high entropy alloys. Intermetallics 2023, 153, 107775. [Google Scholar] [CrossRef]
  26. Churyumov, A.Y.; Pozdniakov, A.V.; Bazlov, A.I.; Mao, H.; Polkin, V.I.; Louzguine-Luzgin, D.V. Effect of Nb Addition on Microstructure and Thermal and Mechanical Properties of Fe-Co-Ni-Cu-Cr Multiprincipal-Element (High-Entropy) Alloys in As-Cast and Heat-Treated State. JOM 2019, 71, 3481–3489. [Google Scholar] [CrossRef]
  27. Ye, X.C.; Wang, T.; Xu, Z.Y.; Liu, C.; Wu, H.H.; Zhao, G.W.; Fang, D. Effect of Ti content on microstructure and mechanical properties of CuCoFeNi high-entropy alloys. Int. J. Miner. Metall. Mater. 2020, 27, 1326. [Google Scholar] [CrossRef]
  28. Wu, Y.; Li, Y.; Liu, X.; Wang, Q.; Chen, X.; Hui, X. High strength NiMnFeCrAlCu multi-principal-element alloys with marine application perspective. Scr. Mater. 2021, 202, 113992. [Google Scholar] [CrossRef]
  29. Shu, C.; Yao, Z.; Li, X.; Du, W.; Tao, X.; Yang, H. Microstructure and wear mechanism of CoCrCuFeNiVx high entropy alloy by sintering and electron beam remelting. Phys. B Condens. Matter 2022, 638, 413834. [Google Scholar] [CrossRef]
  30. Loginov, P.A.; Zhassay, U.A.; Bychkova, M.Y.; Petrzhik, M.I.; Mukanov, S.K.; Sidorenko, D.A.; Orekhov, A.S.; Rupasov, S.I.; Levashov, E.A. Chromium-doped Fe-Co-Ni binders for diamond cutting tools: The features of the structure, mechanical properties, and adhesion to diamond. Int. J. Refract. Met. Hard Mater. 2020, 92, 105289. [Google Scholar] [CrossRef]
  31. Loginov, P.A.; Levashov, E.A.; Kurbatkina, V.V.; Zaitsev, A.A.; Sidorenko, D.A. Evolution of the microstructure of Cu–Fe–Co–Ni powder mixtures upon mechanical alloying. Powder Technol. 2015, 276, 166–174. [Google Scholar] [CrossRef]
  32. Shkodich, N.F.; Kovalev, I.D.; Kuskov, K.V.; Kovalev, D.Y.; Vergunova, Y.S.; Scheck, Y.B.; Vadchenko, S.G.; Politano, O.; Baras, F.; Rogachev, A.S. Fast mechanical synthesis, structure evolution, and thermal stability of nanostructured CoCrFeNiCu high entropy alloy. J. Alloys Compd. 2022, 893, 161839. [Google Scholar] [CrossRef]
  33. Zhu, Z.G.; Ma, K.H.; Wang, Q.; Shek, H. Compositional dependence of phase formation and mechanical properties in three CoCrFeNi-(Mn/Al/Cu) high entropy alloys. Intermetallics 2016, 79, 1–11. [Google Scholar] [CrossRef]
  34. Wu, M.; Chen, K.; Xu, Z.; Li, D.Y. Effect of Ti addition on the sliding wear behavior of AlCrFeCoNi high-entropy alloy. Wear 2020, 462–463, 203493. [Google Scholar] [CrossRef]
  35. Rogal, Ł. Semi-solid processing of the CoCrCuFeNi high entropy alloy. Mater. Des. 2017, 119, 406–416. [Google Scholar] [CrossRef]
  36. Muangtong, P.; Rodchanarowan, A.; Chaysuwan, D.; Chanlek, N.; Goodall, R. The corrosion behaviour of CoCrFeNi-x (x = Cu, Al, Sn) high entropy alloy systems in chloride solution. Corros. Sci. 2020, 172, 108740. [Google Scholar] [CrossRef]
  37. Park, N.; Watanabe, I.; Terada, D.; Yokoyama, Y.; Liaw, P.K.; Tsuji, N. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy. Metall. Mater. Trans. A. 2015, 46, 1481–1487. [Google Scholar] [CrossRef] [Green Version]
  38. Lim, S.C. The relevance of wear-mechanism maps to mild-oxidational wear. Tribol. Int. 2002, 35, 717–723. [Google Scholar] [CrossRef]
  39. Zaveri, N.; Mahapatra, M.; Deceuster, A.; Peng, Y.; Li, L.; Zhou, A. Corrosion resistance of pulsed laser-treated Ti–6Al–4V implant in simulated biofluids. Electrochim. Acta 2008, 53, 5022–5032. [Google Scholar] [CrossRef]
  40. Öztürk, S.; Alptekin, F.; Önal, S.; Sünbül, S.E.; Şahin, Ö.; İçin, K. Effect of titanium addition on the corrosion behavior of CoCuFeNiMn high entropy alloy. J. Alloys Compd. 2022, 903, 163867. [Google Scholar] [CrossRef]
  41. Yu, Y.; Xu, N.; Zhu, S.; Qiao, Z.; Zhang, J.; Yang, J.; Liu, W. A novel Cu-doped high entropy alloy with excellent comprehensive performances for marine application. J. Mater. Sci. Technol. 2021, 69, 48–59. [Google Scholar] [CrossRef]
Materials 16 01178 g001 550
Figure 1. XRD patterns of MA CoCrFeNi and CoCrCuFeNi powder mixtures.
Figure 1. XRD patterns of MA CoCrFeNi and CoCrCuFeNi powder mixtures.
Materials 16 01178 g001
Materials 16 01178 g002 550
Figure 2. Element distribution map in the CoCrCuFeNi powder subjected to MA.
Figure 2. Element distribution map in the CoCrCuFeNi powder subjected to MA.
Materials 16 01178 g002
Materials 16 01178 g003 550
Figure 3. SEM images of the microstructure of the hot-pressed samples: (a) CoCrFeNi; (b) CoCrCu0.25FeNi; (c) CoCrCu0.5FeNi; (d) CoCrCu0.75FeNi; and (e) CoCrCuFeNi.
Figure 3. SEM images of the microstructure of the hot-pressed samples: (a) CoCrFeNi; (b) CoCrCu0.25FeNi; (c) CoCrCu0.5FeNi; (d) CoCrCu0.75FeNi; and (e) CoCrCuFeNi.
Materials 16 01178 g003
Materials 16 01178 g004 550
Figure 4. XRD patterns of the CoCrCuxFeNi compact samples.
Figure 4. XRD patterns of the CoCrCuxFeNi compact samples.
Materials 16 01178 g004
Materials 16 01178 g005 550
Figure 5. (a) The coefficient of friction as a function of the number of cycles (the counterbody wear is shown in the inset); (b) wear track profiles for the CoCrCuxFeNi samples and (c) 3D images of the wear tracks.
Figure 5. (a) The coefficient of friction as a function of the number of cycles (the counterbody wear is shown in the inset); (b) wear track profiles for the CoCrCuxFeNi samples and (c) 3D images of the wear tracks.
Materials 16 01178 g005
Materials 16 01178 g006 550
Figure 6. The effect of copper on hardness (HV), the elastic modulus (E, GPa), and wear of CoCrCuxFeNi.
Figure 6. The effect of copper on hardness (HV), the elastic modulus (E, GPa), and wear of CoCrCuxFeNi.
Materials 16 01178 g006
Materials 16 01178 g007 550
Figure 7. SEM images of the abrasive grooves in the samples: (a) CoCrFeNi; (b) CoCrCu0.25FeNi; (c) CoCrCu0.5FeNi; (d) CoCrCu0.75FeNi; (e) CoCrCuFeNi.
Figure 7. SEM images of the abrasive grooves in the samples: (a) CoCrFeNi; (b) CoCrCu0.25FeNi; (c) CoCrCu0.5FeNi; (d) CoCrCu0.75FeNi; (e) CoCrCuFeNi.
Materials 16 01178 g007
Materials 16 01178 g008 550
Figure 8. Concentration of elements in the areas where oxidative (a) and abrasive wear (b) predominate.
Figure 8. Concentration of elements in the areas where oxidative (a) and abrasive wear (b) predominate.
Materials 16 01178 g008
Materials 16 01178 g009 550
Figure 9. A TEM image of the products in the tribolayer and electron diffraction (a); a HR-TEM image of tribolayer particles in the area shown with a yellow rectangle (b); the distribution maps of elements in the agglomerate of tribolayer particles (c).
Figure 9. A TEM image of the products in the tribolayer and electron diffraction (a); a HR-TEM image of tribolayer particles in the area shown with a yellow rectangle (b); the distribution maps of elements in the agglomerate of tribolayer particles (c).
Materials 16 01178 g009
Materials 16 01178 g010 550
Figure 10. The polarization curves of CoCrCuxFeNi in 3.5% NaCl solution.
Figure 10. The polarization curves of CoCrCuxFeNi in 3.5% NaCl solution.
Materials 16 01178 g010
Table
Table 1. Tribological properties of HEAs.
Table 1. Tribological properties of HEAs.
SampleReduced Wear, 10−5·mm3/N·mCoefficient of Friction (COF)
SampleCounterbodyInitialMaximumAverage
CoCrFeNi6.680.910.090.810.67
CoCrCu0.25FeNi5.170.700.120.830.68
CoCrCu0.5FeNi5.580.850.160.850.69
CoCrCu0.75FeNi8.880.790.290.810.68
CoCrCuFeNi10.541.430.410.850.71
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Mukanov, S.; Loginov, P.; Fedotov, A.; Bychkova, M.; Antonyuk, M.; Levashov, E. The Effect of Copper on the Microstructure, Wear and Corrosion Resistance of CoCrCuFeNi High-Entropy Alloys Manufactured by Powder Metallurgy. Materials 2023, 16, 1178. https://doi.org/10.3390/ma16031178

AMA Style

Mukanov S, Loginov P, Fedotov A, Bychkova M, Antonyuk M, Levashov E. The Effect of Copper on the Microstructure, Wear and Corrosion Resistance of CoCrCuFeNi High-Entropy Alloys Manufactured by Powder Metallurgy. Materials. 2023; 16(3):1178. https://doi.org/10.3390/ma16031178

Chicago/Turabian Style

Mukanov, Samat, Pavel Loginov, Alexander Fedotov, Marina Bychkova, Maria Antonyuk, and Evgeny Levashov. 2023. "The Effect of Copper on the Microstructure, Wear and Corrosion Resistance of CoCrCuFeNi High-Entropy Alloys Manufactured by Powder Metallurgy" Materials 16, no. 3: 1178. https://doi.org/10.3390/ma16031178

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop