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Article

Microstructure, Hardness and Tribological Characteristics of High-Entropy Coating Obtained by Detonation Spraying

by
Zhuldyz Sagdoldina
1,
Laila Sulyubayeva
1,
Dastan Buitkenov
1 and
Yedilzhan Kambarov
1,2,*
1
Research Center “Surface Engineering and Tribology”, Sarsen Amanzholov East Kazakhstan University, Ust-Kamenogorsk 070002, Kazakhstan
2
International School of Engineering, Daulet Serikbayev East Kazakhstan Technical University, Ust-Kamenogorsk 070003, Kazakhstan
*
Author to whom correspondence should be addressed.
Crystals 2025, 15(7), 625; https://doi.org/10.3390/cryst15070625
Submission received: 1 June 2025 / Revised: 22 June 2025 / Accepted: 26 June 2025 / Published: 4 July 2025
(This article belongs to the Section Crystalline Metals and Alloys)
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Abstract

In this study, powders based on a high-entropy AlCoCrFeNi alloy obtained by mechanical alloying were successfully applied to a 316L stainless steel substrate by detonation spraying under various conditions. Their microstructural features, phase composition, hardness, and wear resistance were studied. A comparative analysis between the initial powder and the coatings was performed, including phase transformation modeling using Thermo-Calc under non-equilibrium conditions. The results showed that the phase composition of the powder and coatings includes body-centered cubic lattice (BCC), its ordered modification (B2), and face-centered cubic lattice FCC phases, which is consistent with the predictions of the Scheil solidification model, describing the process of non-equilibrium solidification, assuming no diffusion in the solid phase and complete mixing in the liquid phase. Rapid solidification and high-speed impact deformation of the powder led to significant grain refinement in the detonation spraying coating, which ultimately improved the mechanical properties at the micro level. The data obtained demonstrate the high efficiency of the AlCoCrFeNi coating applied by detonation spraying and confirm its potential for use in conditions of increased wear and mechanical stress. AlCoCrFeNi coatings may be promising for use as structural materials in the future.

1. Introduction

The history of high-entropy alloys (HEAs) as a separate class of multicomponent alloys can be traced back to 2004, when independent research groups, Yeh et al. [1] and Cantor et al. [2], first reported on the potential properties of multicomponent alloys. The term “high-entropy alloy” was first used in the works of Professor Yeh, who suggested that HEAs could be distinguished from other multicomponent alloys by four properties, such as high entropy, distorted lattices, slow diffusion, and the cocktail effect [3,4]. Subsequently, the cocktail effect was excluded from the list of distinctive properties of HEA, since this effect can also occur in other multicomponent systems [5]. The scientific community’s interest in this concept of alloys has grown in recent decades, leading to a noticeable increase in the number of studies on the properties of HEA-based alloys and coatings. It was noted that high-entropy alloys consist of five or more principal elements in near-equiatomic or equimolar ratios, with individual element concentrations ranging from 5 to 35 at.%. This concentration range was proposed on the basis that the maximum entropy value is achieved at an equimolar or near-equimolar ratio of elements. A distinctive feature of such alloys is the predominant formation of disordered solid solutions, the stability of which is ensured by high mixing entropy. That is, a single-phase stable thermodynamically stable substitution solution is formed in the HEA, predominantly possessing an FCC or BCC lattice [1]. This is justified by Boltzmann’s hypothesis, according to which the configurational entropy increases with an increase in the number of different elements in the system. An increase in the value of configurational entropy in both the liquid and solid phases contributes to the formation of a single-phase disordered solid substitution solution with a simple crystal lattice, which is thermodynamically advantageous compared to multiphase solutions. Therefore, the tendency to form ordered structures decreases due to the minimization of Gibbs free energy [6].
The most common of the studied HEA are AlCoCrFeNi and CoCrFeNiMn, which are characterized by simple phase structures of solid solution. For the quasi-four-component CoCrFeNi alloy, FCC is usually recorded as the main phase. However, when the CoCrFeNi alloy is doped with aluminum (Al) in an equimolar ratio, the BCC and B2 phases become dominant [7]. And when the CoCrFeNi alloy is doped with manganese (Mn) in an equimolar ratio, an FCC solid solution is formed [8].
According to scientific research, coatings based on AlCoCrFeNi and CoCrFeNiMn HEA demonstrate high strength and plasticity [9], high wear resistance [10,11], corrosion resistance [12], fatigue resistance [13], and oxidation resistance [14,15]. The unique microstructure and combination of properties indicate the promising application of HEA for both structural and functional products [16,17,18].
The development of HEAs has expanded the possibilities for innovative alloy design, and research is currently focused on studying various approaches to selecting compositions and manufacturing methods, which makes it possible to obtain a variety of phase and microstructural characteristics to achieve the required properties for a specific task. Most HEAs have been obtained by traditional melting and casting methods [19], as well as by powder metallurgy methods [20]. However, HEA-based coatings (HEC) obtained by thermal spraying methods need to be investigated to find a more effective application method for obtaining high-quality HEA coatings. One of the less studied methods of thermal spraying of HEA is the detonation spraying method. Detonation spraying (DS) is a modern and highly effective method of thermal spraying, which is widely used in industry to obtain coatings with a dense microstructure and high adhesion [21]. Unlike other thermal spraying methods, this method affects the substrate surface by means of a detonation wave propagating at a speed of 800–1200 m/s, while the detonation products can be heated to 3500–4500 K, and the carrier gas can reach 1000–1500 K [22,23]. Particles accelerated to high speeds have significant kinetic energy and, upon deposition, form a dense coating with pronounced compressive residual stresses, which improves adhesion to the substrate [24]. Due to the extremely short duration of thermal exposure, the DS method effectively suppresses segregation and oxidation processes, limiting heat transfer in the particles [25]. All this makes detonation spraying a promising method for obtaining high-quality protective coatings [8]. Nevertheless, at present, the number of published studies on the use of DS for obtaining HEC remains extremely limited. One such rare work is Liao’s [8] study of the microstructure and mechanical properties of coatings made of high-entropy CoCrFeNiMn alloys obtained by detonation spraying. Consequently, the production of HECs based on AlCoCrFeNi using DS remains unexplored.
AlCoCrFeNi metal powders are usually obtained by arc melting or gas atomization. These approaches predominantly form phases with a body-centered cubic (BCC) lattice and its ordered modification (B2). In particular, in gas-atomized powders, a B2-like structure is observed at certain cooling rates, while in samples obtained by arc melting, a two-phase B2 + BCC state is usually formed [26]. However, these traditional methods of HEA synthesis are characterized by limited flexibility in controlling the structure and phase composition, which hinders their widespread industrial application [27]. In this regard, this work considers the possibility of obtaining HEA-based powders by mechanical alloying followed by coating. The study also uses a computational approach to analyze phase transformations and the evolution of the microstructure of the AlCoCrFeNi alloy under conditions of rapid non-equilibrium solidification, which is characteristic of thermal spraying processes [28].
The object of the study was to understand the behavior of AlCoCrFeNi HEA obtained by mechanical alloying during detonation spraying. To this end, a non-equilibrium phase diagram of AlCoCrFeNi HEA was initially modeled using the Scheil model. This allowed us to hypothesize the possible phases and microstructural features that form under gas-thermal spraying conditions. Next, the experimental results were compared with theoretical predictions. The mechanical properties of the coating were evaluated using microhardness and wear resistance assessment methods, which made it possible to characterize the behavior of the material at various microstructure scales. The data obtained provide a comprehensive picture of the structure, phase composition, and mechanical characteristics of the coating, confirming its potential for use under increased operational requirements.

2. Materials and Methods

2.1. Preparation of AlCoCrFeNi HEA Coatings

Equimolar AlCoCrFeNi HEA powder was obtained by mechanical alloying (MA) on a high energy ball milling Emax (Retsch, Haan, Germany) at a rotation speed of 1500 rpm without the addition of process control agents. As starting materials, high-purity elemental powders of Al, Co, Cr, Fe, and Ni (purity: 99.7%, particle size: 20–40 μm) were employed. The ratio of ball mass to powder mass was 10:1, and the synthesis duration was 1 h. From the obtained powders, particles with sizes up to 63 μm were selected by sieving methods for powders and were used as the starting material for spraying. A Winner2005A (Jinan Winner Particle Instrument Stock Co., Jinan, China) intelligent laser particle size analyzer was used for more accurate particle size analysis. Square samples with sides of 25 mm and a thickness of 3 mm made of stainless steel (SS316L) were used as the substrate material; the chemical composition is presented in Table 1. Before spraying, the samples were sandblasted to obtain a rough surface, after which the substrates were blown with compressed air and washed with 95% alcohol in an ultrasonic bath to ensure that there were no sand residues on the substrate surface. The AlCoCrFeNi coating was applied using a CCDS2000 computerized detonation spraying system (Siberian Protective Coatings Technologies, Novosibirsk, Russia), as shown in Figure 1. The spraying process was carried out in an open atmosphere.
During the DS process, oxygen and acetylene were used as the fuel (working) gas, and nitrogen was used as the purge gas. The working gas was ignited by a spark plug and detonated [29]. Then, AlCoCrFeNi powders were heated with explosive gas and deposited at high speed onto the substrate, forming a HEC. The parameters of the detonation spraying (DS) process are mainly controlled by the ratio of acetylene to oxygen and the total gas flow rate [29]. In this study, a fixed C2H2/O2 ratio of 1.026 was used to apply coatings of the high-entropy AlCoCrFeNi alloy, and the filling of the barrel with the explosive mixture (percentage of gas filling) varied from the total volume of the barrel. The percentage of gas filling directly affects the thermal and kinetic energy of the particles during spraying, which, in turn, affects the phase composition, microstructure, density, and mechanical properties of the resulting coating. More detailed spraying parameters are presented in Table 2.

2.2. Predictions Using Thermo-Calc

To simulate the equilibrium and non-equilibrium phase diagrams of the equiatomic AlCoCrFeNi HEA, Thermo-Calc software (version 2025a, Thermo-Calc Software, Stockholm, Sweden) [30] was used with the TCHEA7.0 database of high-entropy alloys. The equilibrium diagram was constructed assuming thermodynamic equilibrium, in which the system reaches a stable state with minimum Gibbs energy at a given temperature. For further modeling of high-speed cooling, which is characteristic of DS, a non-equilibrium diagram was constructed using the Scheil-Gulliver model [31] (Figure 2b). The Scheil-Gulliver model assumes that there is no diffusion in the solid state, and diffusion occurs infinitely fast in the liquid state. Furthermore, Scheil is applicable to rapid cooling processes (>103 K/s) [7,28]. The obtained predictions for the phase composition for both equilibrium and non-equilibrium conditions were compared with the phases observed in the coating applied by the DS method. These conditions help us to understand which variables are most important for the operation of the system. Modeling helps to predict the behavior of materials under certain conditions, which allows for a deeper understanding of their properties. This predictive capability is valuable when developing materials for specific applications.

2.3. Microstructural and Phase Composition Analysis

Cross-sections of the coatings were prepared for microstructural analysis. The coating samples were cut using a low-speed cutting machine with a diamond disc, perpendicular to the direction of spraying. The resulting pieces were fixed in thermosetting resin to facilitate mechanical processing. Grinding and subsequent polishing of the samples was carried out in stages.
The microstructure of the powder and cross-section of the samples was studied using a SEM3200 (CIQTEK, Hefei, China) scanning electron microscope with autoemission at an accelerating voltage of 15 keV and a working distance of 10 mm. The chemical composition was analyzed using energy dispersive X-ray spectroscopy (EDS) XFlash 730M-300 (Bruker, Hamburg, Germany).
X-ray diffraction (XRD) analysis of the powder and coating was performed on a diffractometer (X’PertPRO, PANalytical, Almelo, The Netherlands) with Cu Kα radiation (λ = 0.154056 nm). The scanning range was from 20° to 90°, with a scanning speed of 0.02°/s. The obtained data were analyzed using HighScore Plus v.5.2.0 software (PANalytical, Almelo, The Netherlands) to determine the crystal lattice parameters and phase composition using the quantitative Rietveld analysis method.

2.4. Microhardness and Tribological Analysis

The microhardness of the AlCoCrFeNi HEA coating was determined using the Vickers method with a Fischerscope HM2000 microhardness tester (Helmut Fischer GmbH, Sindelfingen, Germany) at a load of 100 mN and an exposure time of 15 s. The average thickness of the coatings was about 100 μm. To increase the accuracy of the measurements, each coating was tested nine times; the measurement points were arranged in a 3 × 3 matrix, and the distance between adjacent points was 30 μm.
The dry sliding wear resistance of the AlCoCrFeNi coating was evaluated by unidirectional sliding using the pin-on-disc method with a TRB3 tribometer (Anton Paar, Graz, Austria). The measurements were performed at a laboratory temperature of 28.07 °C and a relative humidity of 25.05%. A steel ball with a coating and a 100Cr6 steel substrate, cleaned with an ethanol (C2H5OH) solution, was used as the counter body, with a vertical load of 10 N. The test parameters included a sliding distance of 1000 m, a sliding speed of 0.1 m/s, and a wear track width of 10 mm.

3. Results and Discussion

3.1. Phase Predictions Based on Thermo-Calc Data

During modeling, the temperature range was set from 0 to 1600 °C in increments of 200 °C, and the volume fraction of phases was set in the range from 0.0 to 1.0 in increments of 0.1 (Figure 2a). The phase diagram of AlCoCrFeNi (Figure 2a) shows that at high temperatures (~1450 °C) the system is in a completely liquid state. As the temperature decreases, the BCC, B2, σ-phase, and FCC-L12 phases are formed sequentially. At intermediate stages, the coexistence of several phases is observed, including two different variants of the ordered B2 phase (designated as BCC B2 and BCC B2#2). σ-phases are formed in the temperature range from 447 °C to 990 °C, and FCC L12 phases, which are formed in the temperature range from 440 °C to 1345 °C, indicate the complexity of phase transformations during slow cooling. In addition, the equilibrium phase diagram in Figure 2a is similar to those reported in the literature [7], including works based on various thermodynamic databases. In the Thermo-Calc software, different B2 designations (B2 and B2#2) indicate different chemical composition variants in the ordered BCC crystal structure. At room temperature, both the BCC and B2 (B2 and B2#2) phases are stable in the AlCoCrFeNi HEA, as shown in Figure 2.
Figure 2b shows a non-equilibrium phase diagram constructed using the Scheil simulation method, reflecting the rapid cooling conditions characteristic of the DS thermal spraying process (~105–106 K/s [32]). The diagram shows the sequence of phases formed during solidification. The first phase to crystallize is BCC B2, followed by BCC B2#2, FCC L12, and others. Unlike the equilibrium diagram, here there is a delay in the formation of intermetallic and more stable phases, which is associated with limited diffusion at high cooling rates. This confirms the possibility of forming a simplified microstructure when using high-energy deposition technologies, such as detonation spraying. Moreover, the result shows that the σ-phase, which is expected in the equilibrium case, does not form during rapid solidification under high-speed cooling conditions.

3.2. Phase and Microstructural Analysis

When this alloy is synthesized by powder metallurgy, for example, by mechanical alloying, the formation of the alloy depends on the grinding parameters—primarily on the duration of grinding, among other things. Since the initial phases of pure elements are FCC (Ni, Al), BCC (Cr, Fe) and HCP (Co), and the enthalpies of mixing of each binary pair of elements are different, the grinding parameters will determine how much energy is introduced into the system during mechanical alloying and whether it is sufficient to cause mixing between the elements on an atomic scale [33,34]. The morphological features of AlCoCrFeNi powder obtained by mechanical alloying are shown in Figure 3. The particles had a flake-like shape, which is characteristic of powders obtained by mechanical alloying. The particle size of the powder was determined by particle size analysis and characterized by the following values: d10 = 22.020 μm, d50 = 31.133 μm, and d90 = 43.993 μm. The calculation revealed that the average particle size is 32.296 μm. The insert in Figure 3 shows the actual elemental content of the HEA powders, measured by EDS, which is very close to the equal-atomic ratio.
Figure 4 shows the X-ray diffraction (XRD) patterns of the initial AlCoCrFeNi VES powders obtained by mechanochemical synthesis (MA) and the AlCoCrFeNi HEA coatings applied by DS under various conditions. A similar phase composition has already been mentioned in previous works [35,36]. The results for MA HEA powders are consistent with the equilibrium diagram for this alloy, where BCC/B2 phases predominate. All diffractograms identify the following phases: solid solution with a body-centered cubic lattice (BCC), its ordered modification (B2), and a phase with a face-centered cubic lattice (FCC). The phase quantitative analysis of mechanically alloyed (MA) AlCoCrFeNi powder and DS coatings is summarized in Table 3. As can be seen from the quantitative phase analysis data, there is a marked change in the phase composition when transitioning from powder to a coating obtained by detonation spraying. The initial powder mainly consists of BCC and B2 phases (75 ± 1 wt.%) with a smaller proportion of the FCC phase (25 ± 1 wt.%). After spraying, the proportion of the FCC phase gradually increases with the increase in the percentage of gas filling. In particular, the FCC phase content increases from 23 ± 1 wt.% in DS1 to 48 ± 1 wt.% in DS3, while the content of the BCC and B2 phases decreases accordingly. This trend indicates that an increase in detonation energy (as a result of an increase in the volume of the gas mixture) contributes to the redistribution of atoms and phase transformations towards the formation of an FCC-type structure. The observed phase transformation corresponds to thermally activated changes characteristic of high-entropy alloys, where an increase in local temperature and a high cooling rate can contribute to the formation of a more densely packed FCC phase. The change in phase balance has a noticeable effect on the mechanical and tribological properties of coatings, which is discussed in the following sections. In sample DS 1, the BCC and B2 peaks are broad and weakly pronounced, which may indicate a fine-grained structure and high residual stress. In samples DS 2 and DS 3, the peaks become narrower and more intense, which indicates improved crystallinity and possible grain coarsening due to a local thermal effect or partial annealing during the deposition of particles with high kinetic energy. The FCC phase is retained in all coatings in insignificant quantities. Experimentally, the FCC phase was observed in many studies in the temperature range of 600–1100 °C [35,37]. Other studies of the AlCoCrFeNi-based high velocity air fuel (HVAF) spraying coating show somewhat different results, in particular the absence of the FCC phase in the HVAF coating; this is explained by the “low thermal impact” of the HVAF process [30,36].
The obtained experimental data are in good agreement with the results of Thermo-Calc modeling (Figure 2a), according to which, during equilibrium cooling, transitions through the multiphase region with the formation of BCC, B2, FCC, and σ phases are possible in the AlCoCrFeNi system. However, the formation of sigma (σ) phases is significantly suppressed during rapid cooling. The Scheil model (Figure 2b), simulating nonequilibrium solidification, shows that the B2 phase crystallizes first, followed by BCC, and the formation of FCC and other intermetallics practically does not occur, which is due to limited diffusion. Cooling rates typical for detonation spraying (~105–106 K/s) create conditions close to those simulated within the Scheil scheme. This promotes thermodynamic stabilization of the BCC and B2 phases and suppression of the formation of brittle intermetallic compounds. Thus, the simple phase structure observed in the coatings is explained by nonequilibrium solidification conditions.
In general, the detonation spraying method ensures the formation of a stable three-phase BCC + B2 and FCC structure in AlCoCrFeNi-based coatings due to high cooling rates and rapid crystallization. A high degree of agreement between the experimental data and results of numerical simulation confirms the applicability of the Thermo-Calc and Scheil approaches for predicting the phase evolution of HEC obtained by detonation spraying.
The coating/substrate cross-section was characterized by BSE-SEM to evaluate the adhesion quality and possible chemical interactions at the interfaces. As shown in Figure 5, all coatings obtained by the detonation spraying method exhibit good adhesion to the stainless-steel substrate (SS316L), while the coating thickness is 100 μm. In addition, no significant cracks, pores, or other defects are observed at the coating/substrate interface and in the coating bulk.
The results of energy dispersive spectroscopy (EDS) analysis presented in Table 4 demonstrate the distribution of atomic concentrations of the main elements in coatings obtained under various detonation spraying regimes. For each regime, both the values obtained from the distribution maps (map) and from linear scanning of the cross-section (line) are given.
In general, there is satisfactory agreement between the regimes, which confirms the homogeneity of the composition. However, in samples DS2 and DS3, there are some differences between the map and line values, especially in the oxygen content, which may indicate the presence of oxide inclusions. For sample DS3, obtained at the maximum gas filling percentage, a noticeable increase in oxygen content was up to 23.06 at% according to the map and 15.93 at% according to the line, which may be associated with a higher particle temperature and increased oxidation of aluminum and chromium during spraying. Thus, the data obtained confirm the influence of the energy parameters of the spraying process on the elemental composition and degree of oxidation of the coatings, which further affects their microstructure and functional properties. Oxidation of powders is a typical phenomenon for thermal spraying methods [7].
The microhardness of the coatings was measured in the cross-section, perpendicular to the boundary between the coating and the substrate. Five measurement points were located along the perpendicular to the coating surface with a step of 30 μm. The substrate, which is stainless steel (SS316L), demonstrates an average microhardness value of 212 HV. All coatings obtained by the detonation spraying method showed significantly higher microhardness values compared to the substrate. For the coating obtained in the regime DS 1, the microhardness values change from 234 HV near the boundary with the substrate to 468 HV in the outer layers of the coating. At the same time, the coating in the regime DS 2 demonstrates higher microhardness values compared to the previous systems—from 235 HV to 479 HV. The highest microhardness values were recorded for the coating in the regime DS 3, where the hardness was in the range from 225 HV to 648 HV. The microhardness values of the coatings obtained by us are lower than those of the HVAF-based AlCoCrFeNi coatings [7], which are on average ~845 HV, at the same time these coatings are more susceptible to wear than the coatings obtained by the DS method. We also assume that the authors [7] attribute this to the presence of only the BCC phases, while according to our X-ray diffraction results, in addition to the BCC, the FCC and B2 phases were formed, which contributed to the improvement of the wear resistance of the coatings obtained by the DS method.
The dry friction test results presented in Table 5 and Figure 6 showed differences in the wear resistance of the coatings depending on the detonation spraying regime. The lowest volumetric wear was demonstrated by the DS 1 coating, for which the value was 0.0001483 mm3/N × m, which indicates its high wear resistance. With the DS 2 spraying regime, the wear volume value was 0.0002829 mm3/N × m, which is approximately 1.9 times higher than that of DS 1. The DS 3 coating showed an intermediate wear value of 0.0002497 mm3/N × m. The increase in wear volume in the DS 2 and DS 3 samples is associated with a change in the coating microstructure—in particular, with an increase in the number of oxide inclusions and a possible decrease in the density of the lamellar structure at higher particle temperatures. It is also likely that the more complete melting of particles in DS 2 and DS 3 may have had an effect, which could have contributed to the formation of weaker areas with reduced resistance to abrasive and fatigue wear. Thus, the DS 1 coating, formed at a low percentage of gas filling, demonstrates the best combination of density, microstructural homogeneity, and wear resistance under dry friction conditions.

4. Conclusions

AlCoCrFeNi alloy coatings were successfully applied to a 316L stainless steel substrate using detonation spraying, and their unique microstructural and mechanical properties were studied. The phase and microstructural differences between the powder and the coatings were evaluated, and a micro-scale analysis of the mechanical properties was performed. In addition, the tribological characteristics of the coating were investigated by means of a dry sliding wear test at room temperature. The main conclusions are as follows:
-
Phase analysis of AlCoCrFeNi HEA showed that the gas-sprayed powder consisted of BCC + B2 + FCC phases. The phase composition of the powder obtained by mechanical alloying and the coating is consistent with the calculated phase predictions obtained using Thermo-Calc modeling under non-equilibrium cooling conditions.
-
The microhardness of the AlCoCrFeNi coating increased from DS 1 (234–468 HV) to DS 2 (235–479 HV), reaching a maximum of 648 HV for the DS 3 coating. However, the obtained values are inferior to previously published data for AlCoCrFeNi coatings applied by the HVAF method (~845 HV) [7], which is probably due to the formation of the FCC phase, which reduces hardness.
-
Dry friction wear showed differences in the wear resistance of coatings depending on the spraying regime. The DS 1 coating had the lowest volumetric wear (0.0001483 mm3/N × m), while DS 2 and DS 3 had higher values—0.0002829 mm3/N × m and 0.0002497 mm3/N × m, respectively. The increase in wear volume for DS 2 and DS 3 coatings is associated with the presence of oxide inclusions and a possible decrease in the density of the lamellar structure due to more intense particle melting and thermal exposure.
According to the results of our study, AlCoCrFeNi wind turbine coatings prepared by detonation spraying have better characteristics and are promising for future structural applications.

Author Contributions

Conceptualization, Z.S. and Y.K.; methodology, L.S.; investigation, D.B.; writing—original draft preparation, Y.K. and D.B.; writing—review and editing, Z.S.; project administration, L.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP22787411).

Data Availability Statement

The data are contained within the article.

Conflicts of Interest

The authors declare that there are no conflicts of interest regarding the publication of this manuscript.

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Crystals 15 00625 g001
Figure 1. (a) Detonation complex CCDS2000; (b) schematic diagram of AlCrCoFeNi HEC prepared by DS system.
Figure 1. (a) Detonation complex CCDS2000; (b) schematic diagram of AlCrCoFeNi HEC prepared by DS system.
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Figure 2. (a) Equilibrium and (b) phase diagram of the Scheil simulation for AlCoCrFeNi HEA, obtained using Thermo-Calc software.
Figure 2. (a) Equilibrium and (b) phase diagram of the Scheil simulation for AlCoCrFeNi HEA, obtained using Thermo-Calc software.
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Figure 3. SEM micrographs of AlCoCrFeNi HEA powders with EDS element distribution diagram.
Figure 3. SEM micrographs of AlCoCrFeNi HEA powders with EDS element distribution diagram.
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Figure 4. XRD patterns of the AlCoCrFeNi HEA powders and the corresponding HEA coatings.
Figure 4. XRD patterns of the AlCoCrFeNi HEA powders and the corresponding HEA coatings.
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Figure 5. SEM micrographs of AlCoCrFeNi HEA coatings: (a) DS 1, (b) DS 2, (c) DS 3 with the EDS element distribution diagram (The green line shows the scanning area).
Figure 5. SEM micrographs of AlCoCrFeNi HEA coatings: (a) DS 1, (b) DS 2, (c) DS 3 with the EDS element distribution diagram (The green line shows the scanning area).
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Figure 6. SEM of the worn surfaces of the HEC AlCoCrFeNi after dry sliding wear testing.
Figure 6. SEM of the worn surfaces of the HEC AlCoCrFeNi after dry sliding wear testing.
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Table 1. Chemical composition of SS316L.
Table 1. Chemical composition of SS316L.
ElementCSiMnPSCrNiMoNFe
wt.%≤0.03≤1.00≤2.00≤0.0450.0316.00–18.0010.00–14.002.00–3.00≤0.10Balanced
Table 2. Parameters of AlCrCoFeNi HEC obtained by DS method.
Table 2. Parameters of AlCrCoFeNi HEC obtained by DS method.
RegimesRatio O2/C2H2Distance to Substrate, mmNumber of ShotsDelay Time, sLength of Barrel, mmPercentage of Gas Filling, %
DS 11.026150300.5100054
DS 264
DS 374
Table 3. Phase composition of mechanically alloyed (MA) AlCoCrFeNi powder and DS coatings, determined by Rietveld quantitative analysis.
Table 3. Phase composition of mechanically alloyed (MA) AlCoCrFeNi powder and DS coatings, determined by Rietveld quantitative analysis.
SamplesPhasesPhase Content (wt.%)Lattice Parameter (Å)
PowderBCC and B2
FCC		75 ± 1
25 ± 1		2.874
3.577
DS 1BCC and B2
FCC		77 ± 1
23 ± 1		2.867
3.598
DS 2BCC and B2
FCC		69 ± 1
31 ± 1		2.869
3.614
DS 3BCC and B2
FCC		52 ± 1
48 ± 1		2.8661
3.6231
Table 4. The quantitative elemental composition obtained by EDS corresponds to the elemental maps and line (green line shown inside red dashed rectangle) profiles presented in Figure 5.
Table 4. The quantitative elemental composition obtained by EDS corresponds to the elemental maps and line (green line shown inside red dashed rectangle) profiles presented in Figure 5.
Elements (at%)AlCoCrFeNiO
DS 1map15.88 ± 0.8411.24 ± 0.4216.77 ± 0.5529.99 ± 1.0212.14 ± 0.4813.98 ± 0.62
line15.00 ± 1.2614.63 ± 1.2716.31 ± 1.1727.69 ± 2.1813.60 ± 1.3012.77 ± 1.30
DS 2map15.98 ± 0.8012.63 ± 0.4617.42 ± 0.5626.80 ± 0.8912.90 ± 0.4914.27 ± 0.63
line12.98 ± 0.9513.52 ± 0.9917.36 ± 1.0530.46 ± 2.0013.82 ± 1.1011.88 ± 1.14
DS 3map16.65 ± 0.8110.85 ± 0.4015.04 ± 0.4923.58 ± 0.8010.83 ± 0.4223.06 ± 0.68
line11.49 ± 1.0410.85 ± 1.1418.21 ± 1.5030.17 ± 2.7513.35 ± 1.4915.93 ± 1.63
Table 5. Hardness and Volume wear rate of HEC AlCoCrFeNi.
Table 5. Hardness and Volume wear rate of HEC AlCoCrFeNi.
SamplesAverage Porosity, %Hardness, HVVolume Wear Rate, ×10−4 mm3 × N−1 × m−1
DS 110.9 ± 0.1468 ± 121.483
DS 212.4 ± 0.1479 ± 92.829
DS 311.3 ± 0.1648 ± 142.497
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Sagdoldina, Z.; Sulyubayeva, L.; Buitkenov, D.; Kambarov, Y. Microstructure, Hardness and Tribological Characteristics of High-Entropy Coating Obtained by Detonation Spraying. Crystals 2025, 15, 625. https://doi.org/10.3390/cryst15070625

AMA Style

Sagdoldina Z, Sulyubayeva L, Buitkenov D, Kambarov Y. Microstructure, Hardness and Tribological Characteristics of High-Entropy Coating Obtained by Detonation Spraying. Crystals. 2025; 15(7):625. https://doi.org/10.3390/cryst15070625

Chicago/Turabian Style

Sagdoldina, Zhuldyz, Laila Sulyubayeva, Dastan Buitkenov, and Yedilzhan Kambarov. 2025. "Microstructure, Hardness and Tribological Characteristics of High-Entropy Coating Obtained by Detonation Spraying" Crystals 15, no. 7: 625. https://doi.org/10.3390/cryst15070625

APA Style

Sagdoldina, Z., Sulyubayeva, L., Buitkenov, D., & Kambarov, Y. (2025). Microstructure, Hardness and Tribological Characteristics of High-Entropy Coating Obtained by Detonation Spraying. Crystals, 15(7), 625. https://doi.org/10.3390/cryst15070625

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