
==== Front
Ultrason Sonochem
Ultrason Sonochem
Ultrasonics Sonochemistry
1350-4177
1873-2828
Elsevier

S1350-4177(24)00269-4
10.1016/j.ultsonch.2024.107021
107021
Sono-physico-chemical effect
Study on cavitation erosion-corrosion behavior of CoCrFeNiMoCu0.1 high entropy alloy in 3.5 wt% NaCl solution
Li Liang a
Nie Sijia a
Li Chengtao b
Chen Xin a
Qiao Yanxin yxqiao@just.edu.cn
a⁎
Ma Rongyao c
Chen Zhilin b
Zhang Lianmin lmzhang14s@imr.ac.cn
c⁎
Cui Jie cuijie2006@hotmail.com
d⁎
a School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
b Materials Engineering Technology Center, Suzhou Nuclear Power Research Institute1, Suzhou 215004, China
c CAS Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
d School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
⁎ Corresponding authors. yxqiao@just.edu.cnlmzhang14s@imr.ac.cncuijie2006@hotmail.com
08 8 2024
11 2024
08 8 2024
110 1070219 5 2024
12 7 2024
6 8 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
The challenge of cavitation erosion (CE) in flow-handling components of marine engineering has promoted the development of advanced materials due to safety incidents and economic costs. High entropy alloys (HEAs), known for high hardness and corrosion resistance, emerge as promising candidates. This paper delved into the CE characteristics of CoCrFeNiMoCu0.1 HEA when subjected to the 3.5 wt% NaCl solution, elucidating the synergistic effect of CE-corrosion. The quantitative analysis revealed that CE-corrosion synergy contributed 48.02% to total CE mass loss, primarily attributed to corrosion-induced CE damage. Meanwhile, electrochemical noise (EN) was utilized to reveal the corrosion behavior of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution combined with the morphologies observation and surface roughness. Extended CE time compromised the corrosion resistance of CoCrFeNiMoCu0.1 HEA and diminished the impact of selective phase corrosion on the surface. Eventually, the CE damage mechanism of CoCrFeNiMoCu0.1 HEA was revealed based on pertinent experimental findings. The results showed that with increased CE time, the CoCrFeNiMoCu0.1 HEA transitioned from predominantly extensive exfoliation of the initial FCC phase to further damage of the intermetallic σ and μ phases.

Keywords

Cavitation erosion
High entropy alloys
Synergistic effect
CE mechanisms
==== Body
pmc1 Introduction

Cavitation corrosion (CE) is an inevitable failure form of flow-handling components such as water turbines, propellers, pipelines, etc., in the fluid dynamics environment. It is distinguished by the rapid degradation of material surfaces due to the continuous impact of shock waves and micro-jets released by the implosion of bubbles [1], [2], [3]. The CE degradation process of materials in corrosive solutions is more pronounced compared to deionized water [4]. This is primarily due to the damage caused by the synergistic effects of corrosion and CE playing a crucial role [5], [6], [7]. Consequently, there is a growing emphasis on enhancing the CE resistance of materials. Currently, research predominantly focuses on improving the CE and corrosion resistance of flow-handling components through the utilize of coatings [8], [9], surface modification [10], and the design of new material with high CE and corrosion resistance [11]. Stainless steel (SS) and nickel-aluminum bronze (NAB), renowned for their unique CE resistance, are preferred candidates for manufacturing flow-handling components operation in corrosive environments. However, meeting the growing demands of practical engineering applications in increasingly harsh environments remains a significant challenge [12], [13], [14]. The imperative now is to design new materials with excellent CE resistance.

High entropy alloys (HEAs) are a kind of novel materials known for their exceptional mechanical properties, corrosion resistance, and thermal stability [15], [16], [17]. Noting that HEAs have high mixing-entropy, it is expected to form face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packed (HCP) phases [18], [19]. Researchers are increasingly focuses on the application of HEAs in the conditions of CE, driven by the aforementioned outstanding performances. For example, Zhang et al. [20] documented that the AlCrCoFeNi HEA demonstrated superior CE resistance and higher pitting corrosion resistance compared to 304L SS. Nair et al. [11] conducted a study revealing that the Al0.1CoCrFeNi HEA exhibited a notably longer CE incubation period and a reduced corrosion rate (approximately one-fourth) compared to 316L SS. Additionally, Wu et al. [21] discovered that the hardness of FeCoCrAlNiTi2 HEA was at least 3.6 times that of 304 SS, and demonstrate excellent CE resistance. These studies indicate that HEAs may have the prospects to be successfully used in the field of CE.

In marine conditions, factors such as seawater or microbial corrosion can significantly influence the corrosion resistance behavior of materials. To address these challenges, the addition of alloy elements such as Mo and Cu into CoCrFeNi-based HEAs have been investigated. Notably, Shang et al. [22] observed that the addition of Mo is beneficial for improve the corrosion resistance of CoCrFeNi-based HEAs in corrosive environment. However, the existence of the σ phase could leading to the localized corrosion. Hsu et al. [23] reported that the incorporation of Cu into CoCrFeNi-based HEAs fostered the formation of Cu-rich dendrites, thereby inducing localized corrosion in the 3.5 wt% NaCl solution. Moreover, Yu et al. [24] found that the introduction of Cu can enhance the mechanical characteristics, anti-fouling capability, and corrosion resistance of the AlCoCrFeNiCu0.5 HEA. In marine environment, metallic materials may suffering to the synergistic effects between CE and corrosion. Therefore, understanding the synergistic effects of CE and the corrosion mechanisms of CoCrFeNiMoCu0.1 HEA is crucial.

In this study, we focus on elucidating the CE-corrosion behavior of the CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution. This comprehensive investigation includes assessing cumulative mass loss and mass loss rate, observing morphological damage, and conducting electrochemical evaluations under both quiescent and CE conditions. Furthermore, we delve into the examination of the impact of CE-induced damage on corrosion behavior by utilizing EN analysis. The overarching objective of this paper endeavor is to undertake a quantitative analysis and thorough discussion of the synergistic effect of CE-corrosion, with a specific emphasis on elucidating the CE mechanisms. This work could significantly contribute to the comprehension of the intricate dynamics of CE-corrosion.

2 Experimental

2.1 Materials and sample preparation

The sample utilized in the experiment was as-cast CoCrFeNiMoCu0.1 HEA, with its composition (wt%) outlined in Table 1. High-purity (99.99 %) Co, Cr, Fe, Ni, Mo and Cu metals were employed as raw materials to synthesize HEAs through an argon-protected arc melting method. CE experiments were conducted using the CE testing machine (XOQS-1000, Nanjing Xianou Instruments Co., Ltd.), following the ASTM G32-10 standard [25]. The CE device operated at a frequency of 20 kHz, with an output power of 2.5 kW and an amplitude of 60 μm. The shape and size of the experimental samples were based on our previous paper [26], as illustrated in Fig. 1a. The samples were ground with silicon carbide particles of 240, 400, 800, 1200, and 2000 grit sizes, followed by polishing using 1 μm alumina polishing solution. Finally, the samples were washed with deionized water, alcohol, and dried with hot air.Table 1 Chemical composition of CoCrFeNiMoCu0.1 HEA.

Elements	Co	Cr	Fe	Ni	Mo	Cu	
wt%	17.97	15.87	17.04	17.91	29.27	1.94	

Fig. 1 Shape and size of the experimental samples [26].

2.2 Electrochemical tests

Electrochemical testing was performed on samples with dimensions shown in Fig. 1b. Copper wires were affixed to the rear of the samples and subsequently encapsulated with epoxy, ensuring that the test surface exposed to the solutions is 2.28 cm2. The solutions employed in the experiment included a 3.5 wt% NaCl solution and deionized water, where the 3.5 wt% NaCl solution was obtained by using analytical-grade NaCl and deionized water. The electrochemical tests utilized a three-electrode system comprising the sample as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. The schematic diagram of CE electrochemical equipment is shown in Fig. 2. To investigate the electrochemical behavior during CE, potentiodynamic polarization tests were initially conducted under both quiescent and CE conditions. The tests commenced from an open-circuit potential (OCP) of −300 mV, with a scan rate of 0.33 mV/s. Additionally, an OCP test was performed by alternating 300 s of CE and 300 s of quiescence. Prior to both tests, a pre-run of 1800 s for open-circuit potential (OCP) stabilization was also conducted. The post-CE electrochemical behavior was predominantly evaluated using electrochemical noise (EN) techniques. Two samples with identical CE time were employed as working and counter electrodes, while an SCE was the reference electrode. The EN test was performed within a Faraday cage with continuous data acquisition over a duration of 10 h at a sampling frequency of 10 Hz. Due to the non-stationary nature of the collected EN signal, the db4 wavelet was used to mitigate the DC drift. The data was segmented into chunks of 5120 points each for the subsequent analysis. The acquisition and analysis of the EN data were conducted utilizing both the ES410 software and MATLAB 2018a.Fig. 2 Schematic diagram of CE electrochemical equipment.

2.3 Composition and structure characterization

The phase composition of the CoCrFeNiMoCu0.1 HEA was examined via X-ray diffraction (XRD) analysis using the D8 ADVANCE instrument. Cu Kα radiation (λ = 0.15418 nm), scanning within 2θ range from 20° to 90° with a scanning speed of 4°/min. The microstructure and phase distribution of CoCrFeNiMoCu0.1 HEA were obtained through electron backscatter diffraction (EBSD). The samples underwent vibratory polishing using a 1 μm colloidal SiO2 suspension. EBSD test was performed on a field emission scanning electron microscope (FE-SEM) equipped with an Oxford Instruments Aztec system, with a voltage of 20 kV and a current of 10nA. The analysis of EBSD data was performed using Channel 5 software. The samples used for microstructure and elemental distribution were subjected to further analysis through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS, ZEISS Sigma 500 type). Prior to analysis, the samples were etched in a 10 wt% oxalic acid solution at a voltage of 5 V for 5 s. The microhardness of different regions in the microstructure of CoCrFeNiMoCu0.1 HEA was determined using the KB30S-FA microhardness tester, with a testing load of 200 g and a dwell time of 10 s. The CE damage and roughness variations on the sample surfaces after various CE times was characterized using SEM and confocal laser scanning microscope (CLSM, LEXTOLS4000), respectively.

3 Results and discussion

3.1 Microstructure characterization of CoCrFeNiMoCu0.1 HEA

The XRD spectrum of the CoCrFeNiMoCu0.1 HEA phase composition is revealed in Fig. 3a. The findings suggest that the CoCrFeNiMoCu0.1 HEA predominantly consisted of the FCC phase, together with the precipitation of intermetallic σ and μ phases. It is noted that the σ phase resembles the tetragonal structure of FeMo (a = 9.128 Å, c = 4.813 Å, JCPDS #15–0539), while the μ phase resembles the rhomboidal shape which has been observed in Co7Mo6 (a = 4.757 Å, c = 25.589 Å, c/ a = 5.379, JCPDS #29–0489) [27]. The discovery of XRD is further corroborated by the results obtained from the EBSD and SEM-EDS, as shown in Fig. 3b and 3d. It is reported that the intermetallic compound σ phase precipitates within the FCC phase, forming the granular and lamellar structures, whereas the intermetallic compound μ phase is observed at the interdendritic region and granular σ phase boundaries [27], [28]. The phase distribution of these phases is clearly shown in the results of EBSD (Fig. 3b). For a better understanding of the surface damage caused by CE, the microstructure of CoCrFeNiMoCu0.1 HEA was primarily divided into two regions: granular σ and lamellar σ/interdendritic μ + FCC. The hardness values of these two regions are illustrated in Fig. 3c. The granular σ phase exhibits higher hardness (809.2 HV), surpassing that of the σ/μ + FCC region (567.5 HV). This phenomenon is ascribed to the elevated Mo content observed in the σ phase (Fig. 3d), which increases its hardness [29], [30]. To further investigate the elemental distribution in different phases, the surface morphology of CoCrFeNiMoCu0.1 HEA after etching with oxalic acid solution is characterized using EDS. The SEM-EDS images are depicted in Fig. 3d. The elemental contents of different phases within CoCrFeNiMoCu0.1 HEA with corresponding EDS analyses are summarized in Table 2. The results reveal that the atomic percentages of Cr and Mo account for higher than 50 % in σ and μ phases, and the surface scanning distribution map shows that Mo is more concentrated in the two phases. It is known that the presence of Co and Ni in the austenitic favors to the formation of the FCC phase. However, the presence of Mo and Cr induces the precipitation of the σ phase, owing to their high electron-hole concentrations [28]. In addition, Cu solutes tend to aggregate at dendrite or grain boundaries during solidification due to the high mixing enthalpy of Cu with other elements [23], [31]. The tendency for σ phase precipitation in the FCC phase can be evaluated based on the equivalent Cr content (ECC) [27], [32]:(1) ECC = [\% Cr] + 1.76×[\% Mo] + 0.31×[\% Mn] + 1.7×[\% Nb] + 0.97×[\% W] +2.02×[\% V] + 1.22×[\% Ta] + 2.24×[\% Ti] + 1.58×[\% Si]-0.177×[\% Co]-0.266×[\% Ni]

When the value of ECC is greater than 18, the σ phase is preferentially precipitates within the FCC phase. Herein, the ECC of CoCrFeNiMoCu0.1 HEA is 78.2, the Cr and Mo contents far exceed their solubility in the FCC phase. Thus, the σ phase rich in Cr and Mo is inevitably precipitate within FCC phase. It is well known that the presence of Mo in the σ phase can induce serious lattice strain, this will promot the transformation of σ phase to μ phase during the solidification process [28], [33].Fig. 3 Microstructure characteristics of CoCrFeNiMoCu0.1 HEA: (a) XRD spectrum of CoCrFeNiMoCu0.1 HEA, (b) EBSD results of CoCrFeNiMoCu0.1 HEA including band contrast and phase distribution diagram, where FCC, σ and μ phases are marked in red, yellow and blue, respectively, (c) microhardness of different regions on the surface of CoCrFeNiMoCu0.1 HEA, (d) SEM images and elemental surface scanning distribution map of CoCrFeNiMoCu0.1 HEA after etching.

Table 2 Elemental composition of the points marked in Fig. 2d by EDS.

Point	Co	Cr	Fe	Ni	Mo	Cu	
1-FCC	20.06	19.40	17.04	23.16	19.36	3.43	
2-μ phase	16.07	13.97	14.13	14.12	40.25	1.48	
3-σ phase	15.04	16.67	14.07	11.35	42.21	0.66	

3.2 CE mass loss of CoCrFeNiMoCu0.1 HEA

Fig. 4 depicts the cumulative mass loss and mass loss rate of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution and deionized water at various CE intervals. The result suggest that the cumulative mass loss of CoCrFeNiMoCu0.1 HEA in both 3.5 wt% NaCl solution and deionized water steadily increases with prolonged CE exposure. As shown in Fig. 4a, the cumulative mass loss of CoCrFeNiMoCu0.1 HEA after 8 h CE is 23.75 mg (3.5 wt% NaCl solution) and 10.40 mg (deionized water), respectively. Fig. 4b shows that CoCrFeNiMoCu0.1 HEA exhibits a similar cumulative mass loss rate trend in two test solutions. The cumulative mass loss rate reaching the maximum value after 1 h CE, then decreases and stabilizes after CE for 4 h. For the sample after CE between 4 h and 8 h, the difference in cumulative mass loss rate in two test solutions is about 2 mg/h. It is inferred that the corrosive medium plays a significant influence on the CE damage of CoCrFeNiMoCu0.1 HEA.Fig. 4 Cumulative mass loss (a) and mass loss rate (b) of CoCrFeNiMoCu0.1 HEA after various CE intervals in 3.5 wt% NaCl solution and deionized water.

3.3 Morphologies and roughness of CoCrFeNiMoCu0.1 HEA

Fig. 5 illustrates the surface damage morphologies of CoCrFeNiMoCu0.1 HEA after various CE times in the two test solutions. It is evident that protrusions of σ and μ phases in CoCrFeNiMoCu0.1 HEA after 20 and 40 min of CE in 3.5 wt% NaCl solution (Fig. 5a and 5b). However, in deionized water, the sample surface is relatively smooth, and the protrusion of σ and μ phases is less pronounced (Fig. 5f and 5 g). This is primarily due to the enrichment of Mo elements in the granular σ phase and the lamellar σ/interdendritic μ phase, thereby increasing the hardness of material. The FCC phase with lower hardness is preferentially the damaged by CE impact. After CE for 1 h, damage induced by CE occurs on the granular σ phase o in both test solutions (Fig. 5c and 5 h). In 3.5 wt% NaCl solution, the exfoliation of μ phase at the granular σ phase boundaries is evident, which results in the presence of micro-cracking and further degradation of the FCC. For samples with CE in deionized water, plastic deformation protrusions occur mainly in the FCC phase near the granular σ phase boundary. After 3 h and 7 h CE, the corrosion morphologies of the samples in the two test solutions are more similar (Fig. 5d, 5e, 5i, and 5j), some granular σ phases become smooth under CE impact, and the lamellar σ/interdendritic μ + FCC region also displays the retained σ/μ phases.Fig. 5 Surface morphologies of CoCrFeNiMoCu0.1 HEA after various CE times in 3.5 wt% NaCl solution (a-e) and deionized water (f-j).

Fig. 6 illustrates the surface average roughness (Sa) of the CoCrFeNiMoCu0.1 HEA after various CE times in two test solutions. It is the average of the absolute values of the heights of all points within the examined area. The results show that the Sa value of CoCrFeNiMoCu0.1HEA in 3.5 wt% NaCl increases from 29 nm to 63 nm after 20 min to 1 h of CE, while the Sa value increased from 16 nm to 37 nm in deionized water. The change in Sa is mainly ascribed to dissolution of the FCC phase. After CE for 3 h and 7 h, the Sa in NaCl solution is 86 nm and 844 nm, respectively. While, the Sa in deionized water is 83 nm and 823 nm, respectively. This attributed to the similar damage mechanism of HEA in the two test solutions, characterized by the peeling of the FCC phase on the sample surface.Fig. 6 Surface roughness of CoCrFeNiMoCu0.1 HEA after various CE times in 3.5 wt% NaCl solution (a–e) and deionized water (f–j).

3.4 Surface vickers hardness of CoCrFeNiMoCu0.1 HEA

Fig. 7 illustrates the evolution of hardness in CoCrFeNiMoCu0.1 HEA after varying CE times in deionized water and 3.5 % NaCl solution. Prior to CE, the hardness of the granular σ phase and σ/μ + FCC region is 809.2 Hv and 567.98 Hv, respectively. After 20 min of CE, there is a slight decrease in hardness in both deionized water and 3.5 % NaCl solution. Initially, the formation and collapse of bubbles during CE can cause initial impacts and relief on the sample surface, potentially leading to plastic deformation of the surface, thereby resulting in a slight decrease in surface hardness. With prolonged CE time, the hardness of the CoCrFeNiMoCu0.1 HEA gradually increased, reaching 908.7Hv (granular σ) and 630.26 Hv (σ/μ + FCC) in deionized water and 938.28 Hv (granular σ) and 626.28 Hv (σ/μ + FCC) in 3.5 % NaCl solution after 7h of CE. This increase in hardness is more likely attributed to the formation of work-hardened layer by the repeated impact induced by CE [34]. Furthermore, the CoCrFeNiMoCu0.1 HEA exhibits higher hardness in 3.5 % NaCl solution compared to that in deionized water. This may be due to the salt solution lowering the surface tension of the bubbles, thereby increasing the CE intensity and leading to more significant work hardening [35].Fig. 7 Hardness of CoCrFeNiMoCu0.1 HEA after various CE times.

3.5 Electrochemical behavior of CoCrFeNiMoCu0.1 HEA under CE

Fig. 8a shows the potentiodynamic polarization curves of the CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution under CE and quiescence. CE significantly influences the polarization behavior of HEAs, resulting in a dramatic increase in cathodic reactions, while the anodic response continues to exhibit a well-defined passivation region. The Ecorr and Icorr obtained by Tafel extrapolation fitting are shown in Table 3. The findings indicate that the Ecorr of the CoCrFeNiMoCu0.1 HEA increases from −0.256 VSCE under quiescence to −0.127 VSCE under CE, and the Icorr under CE is 8.78 times of that under quiescence. This may due to the acceleration of oxygen transportation induced by CE, which promotes the reaction rate of the cathode [5], [36]. Additionally, compared to commonly used marine alloys such as the cobalt-based alloy Stellite 706 [37], Inconel 625 [38], and 304 SS [39], the CoCrFeNiMoCu0.1 HEA exhibits a higher Ecorr and a lower Icorr. This indicates that the HEA has superior corrosion resistance in 3.5 % NaCl solution. Fig. 8b depicts the OCP curves for CoCrFeNiMoCu0.1 HEA under periodically switched quiescence and CE conditions. It is evident that the OCP undergoes periodic shifts in both positive and negative directions. This phenomenon is typically associated with the competitive effects of the growth/disruption of the passive film and the increased mass transport of oxygen [40]. The curve shows that an OCP variation of CoCrFeNiMoCu0.1 HEA has four key stages in an alternating CE cycle, the rapid (1) and the gradual (2) positive shift in potential under CE and the rapid (3) and the gradual (4) negative shift in potential under quiescence. The schematic in Fig. 8c illustrates these potential changes for understanding of the OCP response in Fig. 8(b). Initially, the corrosion condition of sample is at point A, with the Ecorr and Icorr, respectively. In stage (1), the CoCrFeNiMoCu0.1 HEA exhibits excellent passive properties at the onset of CE, effectively suppressing the anodic reaction. Simultaneously, rapid oxygen transfer in solution accelerates the cathodic reaction [40], [41]. The cathodic line transforms from A1 to A2, resulting in a rapid positive shift in the Ecorr from point A to point B. The Ecorr is undergoing a rapid positive movement. In stage (2), the passive film on the surface of CoCrFeNiMoCu0.1 HEA protects them from the breakdown of CE. The anodic reaction rate is further suppressed as the passive film continues to grow. The cathodic line remains unchanged, while the anodic line shifts from B1 to B2, causing point B to move towards point C. Consequently, Ecorr gradually shifts to the positive direction. In stage (3), at the moment of cessation of CE, the potential shifts rapidly in a negative direction. This is due to the significant reduction in the oxygen transfer rate after CE stops, leading to a decrease in the cathodic reaction rate, while the anodic reaction rate remains unchanged. The cathodic line shifts from A2 to A3, causing point C to move towards point D. In stage (4), the continuous growth of the passive film on the sample surface consumes oxygen in the solution, thereby reducing the cathodic reaction rate. The cathodic line moves from A3 to A4, causing point D to move towards point E. Additionally, with prolonged exposure to CE, the transition from point B to point C tends to follow a linear trend. This is attributed to the increasing cumulative damage on the sample surface with extended CE time, leading to localized rupture and repassivation of the passive film, and eventually reaching a balance of dynamic equilibrium.Fig. 8 Potentiodynamic polarization curves of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution under quiescence and CE (a), OCP response of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution (b), schematic diagram of the changes in Ecorr and Icorr of CoCrFeNiMoCu0.1 HEA under quiescence and CE (c).

Table 3 Ecorr and Icorr values of CoCrFeNiMoCu0.1 HEA, cobalt-based Alloy, nickel-based alloy, and stainless steel in 3.5 wt% NaCl solution.

Sample	Conditions	Ecorr/(VSCE)	Icorr/(A/cm2)	
CoCrFeNiMoCu0.1	Quiescence	−0.256	1.23 × 10-7	
CE	−0.127	1.08 × 10-6	
Stellite 706 [37]	Quiescence	−0.71	6.66 × 10-5	
Inconel 625 [38]	Quiescence	−0.89	2.81 × 10-5	
304 stainless steel [39]	Quiescence	−0.28	4.75 × 10-7	

3.6 Electrochemical behavior of CoCrFeNiMoCu0.1 HEA after CE

The effect of cumulative surface damage on corrosion behaviours were further analyzed using EN techniques. The EN signals of CoCrFeNiMoCu0.1 HEA immersed in 3.5 wt% NaCl solution after various CE times are illustrated in Fig. 9. Due to complex signal superposition and the occurrence of DC (direct current), the obtained data were processed using wavelet drift reduction technique and displayed in Fig. 10. It is acknowledged that the noise resistance (Rn) is inversely proportional to the corrosion rate of the sample in the corrosive solution [42], [43]. Fig. 10a illustrates the evolution of the entire Rn values during the immersion process. The result shows that the Rn value of the samples gradually stabilized after 6 h of immersion, while continuous CE reduced the Rn amplitude fluctuation during the initial immersing of the sample. This suggests the damaging effect of selective phase corrosion on the passive film of the sample surface continues to weaken. After 6 h immersion, the average Rn value of the samples decreased from 1 × 103 Ω·cm2 before CE to 3 × 102 Ω·cm2 after 7 h of CE, indicating the corrosion resistance of the material decreases continuously with the duration of CE. The deterioration in corrosion resistance of HEA due to the formation of the defects induced by CE attack. Conversely, the removal of the FCC phase under the influence of CE reduces the selective phase corrosion at the sample surface. Further validation of the accuracy of the change of Rn values has been achieved through the use of shot noise and wavelet analysis.Fig. 9 EN signal of CoCrFeNiMoCu0.1 HEA immersed in 3.5 wt% NaCl solution after various CE times.

Fig. 10 EN data of CoCrFeNiMoCu0.1 HEA immersed in 3.5 wt% NaCl solution after various CE times (wavelet removal of direct-current drift): (a) noise resistance (Rn). (b) q vs fn plot based on shot noise, (c) Cumulative distribution plot of fn, (d) cumulative distribution plot of q.

EN signals are typically composed of charge packet that deviate from the baseline, according to the theory of shot noise [44], [45]. Therefore, two characteristic parameters, namely the frequency of corrosion events (fn) and the charge (q) generated by a single corrosion event can be derived from shot noise. These parameters can be calculated from Eq.s (3) and (4) [26], [46]:(2) fn=B2ψES

(3) q=ψEψIB

where ψE and ψI is the low-frequency power spectral density (PSD) values for potential and current noise, respectively. S represents exposed area of the sample, and B is the Stern-Geary coefficient [47]. Subsequently, the values of fn and q are arranged in ascending order, and the cumulative probability is determined using the formula G/(H+1), where G and H represent the order and the total number of fn and q, respectively. Fig. 10b illustrates the fn-q curves of CoCrFeNiMoCu0.1 HEA after immersion in 3.5 wt% NaCl solution at various CE times. It is evident that with increasing CE exposure, the values of fn and q for the CoCrFeNiMoCu0.1 HEA shift towards higher fn and lower q regions, respectively. The increase in q implies that the corrosion activity of the system will increase as a result of a greater charge being generated per corrosion event. While the decrease in fn suggesting the decrease in corrosion events and the corrosion process is more likely to localized corrosion [48], [49]. The q and fn values of the CoCrFeNiMoCu0.1 HEA shift towards lower q and higher fn regions with the extension of CE time. This indicates that the tendency for localized corrosion on the sample surface decreases as CE time increases. Fig. 10c and 10d present cumulative probability plots of fn and q for the CoCrFeNiMoCu0.1 HEA after immersion in 3.5 wt% NaCl solution at various CE times. The results indicate that during the early stages of CE (before 1 h), the values of fn are predominantly distributed within range from 104 Hz to 106 Hz, with q values between 10−13C and 10-11C. As the CE time increases, particularly after 3 h and 7 h CE, the fn values for the samples increase significantly and distributed within the range of 105 Hz–107 Hz, while the q values remain between 10-13C and 10-12C. In addition, the cumulative probability values of q after 3 h and 7 h of CE almost overlap. This indicates that the corrosion rate and the dominate corrosion mechanism of the CoCrFeNiMoCu0.1 HEA in the 3.5 wt% NaCl solution exhibits relatively minor fluctuations with increasing CE exposure time (between 3 h and 7 h). This observation aligns with the findings of the Rn analysis.

Wavelet analysis has unique advantages in processing non-stationary signals, providing time–frequency local information and enabling multi-resolution analysis [50]. It is particularly valuable for transient signals that occur on different time scales. A Discrete Wavelet Transform (DWT) is used to analyze the electrochemical current noise (ECN) data obtained during immersion time of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution. The noise data were simulated in term of detail coefficients (D1–D10) using fourth-order orthogonal Daubechy wavelets (db4). The detailed coefficients are known as D-series crystals. Specific details of the DWT method can be found in literatures [51], [52], [53]. To explore the contribution on different time scales, the energy representation of each crystal calculated and is shown in Fig. 11 [54]. It is well known that for passivating systems, crystals D1–D4 (high frequency) are associated with passivation or initiation of pitting, while the intermediate frequency range of D4–D7 represents the growth of metastable pitting and D7–D10 is associated with the growth of stable pitting or selective phase corrosion [54], [55], [56]. During the early immersion period (6 h) for the sample without CE, the relative energy mainly distribute in the D7–D10 region corresponds to selective phase corrosion. When the immersion time longer than 6 h, the relative energy distribute in D1–D4 region implying the formation of passive film (passivation). After 1 h CE, the time required to accumulate relative energy in the D7–D10 region increased to approximately 8 h. This is attributed to the occurrence of damage induced by CE, which makes the passive film susceptible to degradation. The combined effect of damage and re-passive of the passive film causing the relative energy of the D7–D10 region to accumulate in the later stage of immersion. As CE is extended to 3 h and 7 h, the accumulation of relative energy in the D7–D10 region decreases with time, reaching a minimum of 1 h, followed by a shift of the energy distribute mainly in the D1–D4 region. This shift is mainly due to the gradual stripping of the FCC phase during the CE process, which reduces the occurrence of selective phase corrosion.Fig. 11 Energy distribution pots (EDP) of current noise of CoCrFeNiMoCu0.1 HEA immersed in 3.5 wt% NaCl solution after various CE times.

3.7 Synergistic effect between CE and corrosion of CoCrFeNiMoCu0.1 HEA

The synergistic effects of corrosion and CE properties of metallic materials is a critical issues [34]. The mechanical effect of CE can not only accelerates the mass transfer of oxygen and metal ions, but also thinning and/or rupture of the passive film [57]. It is essential to understanding the fundamental mechanisms of the interaction between corrosion on CE damage. Each component contribution to CE can be calculated using the Eq. (4) [7], [58]:(4) T=E+C+EC+CE

where T represents the cumulative mass loss, C and E is the mass loss of pure corrosion and pure CE, respectively, CE and EC represent the mass losses from CE induced corrosion and corrosion induced CE, respectively. The mass loss of C (quiescence condition) and CE' (CE condition) can be calculated by using Icorr from Table 3 using Eq. (5) [59]:(5) Cc= MIcorrnF×A×h

where F represents Faraday constant (96,500C/mol), M is the molar mass of the CoCrFeNiMoCu0.1 HEA, n is the valency (n = 3 in this work), A is the area of the sample, and h is the CE time. The values of CE and EC can be obtained through Eqs. (6), (7):(6) CE=CE′-C

(7) EC=T+E-C-CE

The component of each part calculated are summarized in Table 4. The results indicate that the synergistic part of CE and corrosion (EC+CE) is accounting for approximately 48.02 % of the cumulative mass loss. Therefore, corrosion has a considerable impact on the CE of CoCrFeNiMoCu0.1 HEA in corrosive environment.Table 4 Mass loss induced by pure corrosion, pure erosion, erosion induced corrosion and corrosion induced erosion and ratios of each factor.

	T	E	C	CE	EC	
Mass loss/(mg)Damage fraction /
(%)	27.80
100 %	14.45 (51.97 %)	0.003 (0.01 %)	0.022 (0.07 %)	13.33 (47.95 %)	

3.8 CE mechanism of CoCrFeNiMoCu0.1 HEA

Fig. 12 provides a CE damage mechanisms of the CoCrFeNiMoCu0.1HEA after various CE times in 3.5 wt% NaCl solution. The presence of corrosion can accelerates the damage of materials, the CE damage mechanism of CoCrFeNiMoCu0.1HEA in deionized water is somewhat similar to that in 3.5 wt% NaCl solution, albeit at a relatively slower damage rate. The findings show that the HEA surface damage in 3.5 wt% NaCl solution is mainly manifested as peeling of the FCC phase during the initial CE period (20 min–40 min). This leads to the exposure of the μ phase at the boundaries of the σ phase and the stratification of the σ/μ phase within the σ/μ + FCC region. After 40 min–1h of CE in 3.5 wt% NaCl solutions, CE-induced brittle damage occurs on the σ phase of the sample surface. Furthermore, the small-scale exfoliation of the μ phase at the σ phase boundaries results in micro-cracking. The occurrence of this phenomenon is attributed to a reduction in the bond strength between the phases and the matrix as a result of corrosion [54], [60]. When CE stress is concentrated at the phase boundaries, leading to the spalling of small-sized μ phase and microcracks at the σ phase boundary. The CE damage on the surface of the sample was further intensified after CE for 1 h–7h. Some granular σ phases become smooth under CE pressure, while others undergo brittle peeling. The σ/μ + FCC region also shows predominantly partial residual σ/μ phases and partial overall peeling damage.Fig. 12 CE damage mechanism diagram of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution.

3.9 Application prospects of HEAs in the field of CE

To further explore the potential applications of HEAs in the circumstance of CE, a comprehensive literature review have been carried out on the CE resistance of engineering materials [34], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71]. The relative CE resistance is calculated based on the reciprocal value of the mean depth of erosion (MDE), and the results are shown in Fig. 13. All of the published works were conducted based on ASTM G32-10, with an 8 h CE time in deionized water. The reciprocal of the MDE is a key index to evaluating the CE resistance of the materials. The results show that SS with a hardness between 200 HV and 400 HV exhibits the lowest CE resistance. This is due to its sensitivity to plastic deformation and localized defects during CE. In contrast, TC4 titanium alloy has excellent CE resistance due to its higher hardness of (600 to 1000 HV). Despite NAB having a low hardness (∼300 HV), the CE resistance of NAB is unique. This may be due to the formation of a work-hardened layer during CE and the inhibition of crack propagation through the precipitation of κ phases [54], [57]. Interestingly, ceramics and ceramics coatings exhibit the highest hardness (1000 HV–1400 HV), however, their CE resistance is in no sense as good as desirable. This discrepancy could be attributed to the presence of defects similar to pores. The hardness of the HEA used in this work is similar to that of TC4 titanium alloy, but its CE resistance is far exceeds other materials. The unique microstructure of HEAs allows the balance of high ductility and fracture strength simultaneously [72]. This makes them can be used in high-flow environments such as propellers and turbines.Fig. 13 Comparative analysis of the CE performance and hardness between the sample and commonly used engineering materials [34], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71].

4 Conclusions

The ultrasonic cavitation technique was used to investigate the CE behavior of CoCrFeNiMoCu0.1 HEA in 3.5 wt% NaCl solution. The synergistic effects of corrosion and CE was investigated in derail. In addition, the mechanism of the CE damage was further elucidated and the influence of CE induced damage on the corrosion behavior of HEA in a 3.5 wt% NaCl solution was investigated. The conclusions are as follows:(1) The cumulative mass loss of the CoCrFeNiMoCu0.1 HEA in 3.5 % NaCl solution is significantly affected by the synergistic effect of CE-corrosion, with pure CE accounting for approximately 51.97 %, and the synergistic effect of CE corrosion contributing 48.02 %.

(2) The damage induced by CE, leading to the deuteriation of the corrosion resistance of CoCrFeNiMoCu0.1 HEA. The CE induced removal of the FCC phase effectively mitigated the incidence of selective phase corrosion on the HEA.

(3) The corrosion mechanism of the CoCrFeNiMoCu0.1 HEA primarily entailed the preferential peeling of the FCC phase during the entire CE process. As the CE time increased, some granular σ phases became smoother under the CE pressure, while others experienced brittle detachment. The lamellar σ/interdendritic μ + FCC region mainly showed partial residual σ/μ phases and partial overall detachment damage.

5 Statement of originality

This article has not been published in whole or in part nor is it being considered for publication elsewhere. This work has the full consent of all authors and that if accepted, the article will not be published elsewhere in the same form, in English or in any other language, without the consent of the Publisher.

CRediT authorship contribution statement

Liang Li: Writing – original draft, Investigation, Formal analysis. Sijia Nie: Investigation, Formal analysis. Chengtao Li: Investigation. Xin Chen: Investigation, Formal analysis. Yanxin Qiao: Writing – review & editing, Supervision, Conceptualization. Rongyao Ma: Writing – review & editing, Visualization, Validation. Zhilin Chen: Investigation. Lianmin Zhang: Writing – review & editing, Validation, Supervision, Conceptualization. Jie Cui: Writing – review & editing, Visualization, Validation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

We express our gratitude to the financial support of the National Natural Science Foundation of China (Nos.52101105 and 52271319), the IMR Innovation Fund (2023-PY03) and the Jiangsu Provincial Science and Technology Program (BK20231525).
==== Refs
References

1 Li Z.X. Zhang L.M. Udoh I.I. Ma A.L. Zheng Y.G. Deformation-induced martensite in 304 stainless steel during cavitation erosion: Effect on passive film stability and the interaction between cavitation erosion and corrosion Tribol. Int. 167 2022 107422
2 Fernández-Domene R.M. Blasco-Tamarit E. García-García D.M. García-Antón J. Cavitation corrosion and repassivation kinetics of titanium in a heavy brine LiBr solution evaluated by using electrochemical techniques and Confocal Laser Scanning Microscopy Electrochim. Acta 58 2011 264 275
3 Yang Z. Li L. Qiao Y.X. Li C.T. Zhang L.M. Cui J. Ren D.C. Ji H.B. Zheng Y.G. Cavitation erosion-corrosion properties of as-cast TC4 and LPBF TC4 in 0.6 mol/L NaCl solution: A comparison investigation Ultrason. Sonochem. 108 2024 106947
4 Li L. Qiao Y.X. Zhang L.M. Ma A.L. Daniel E.F. Ma R.Y. Chen J. Zheng Y.G. Effect of cavitation erosion induced surface damage on pitting and passive behaviors of 304L stainless steel Int. J. Miner. Metall. Mater. 30 7 2023 1338 1352
5 Li Y. Lian Y. Sun Y.J. Synergistic effect between cavitation erosion and corrosion for friction stir processed NiAl bronze in artificial seawater Met. Mater. Int. 27 12 2021 5082 5094
6 Bakhshandeh H.R. Allahkaram S.R. Zabihi A.H. Barzegar M. Evaluation of synergistic effect and failure characterization for Ni-based nanostructured coatings and 17–4PH SS under cavitation exposure in 3.5 wt % NaCl solution Wear 466–467 2021 203532
7 Song Q.N. Tong Y. Li H.L. Zhang H.N. Xu N. Zhang G.Y. Bao Y.F. Liu W. Liu Z.G. Qiao Y.X. Corrosion and cavitation erosion resistance enhancement of cast Ni–Al bronze by laser surface melting J. Iron Steel Res. Int. 29 2 2022 359 369
8 Zhang H.J. Chen X.Y. Gong Y.F. Tian Y. McDonald A. Li H. In-situ SEM observations of ultrasonic cavitation erosion behavior of HVOF-sprayed coatings Ultrason. Sonochem. 60 2020 104760
9 Qiao L. Wu Y.P. Hong S. Cheng J.B. Zhu S.S. Influence of annealing on microstructure and cavitation erosion resistance of iron-based metallic glass coatings synthesized by HVOF thermal spraying Intermetallics 161 2023 107970
10 Qin Z.B. Zhang Q. Luo Q. Wu Z. Shen B. Liu L. Hu W.B. Microstructure design to improve the corrosion and cavitation corrosion resistance of a nickel-aluminum bronze Corros. Sci. 139 2018 255 266
11 Nair R.B. Arora H.S. Mukherjee S. Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy Ultrason. Sonochem. 41 2018 252 260 29137749
12 Wang Z.Y. Cheng H.Y. Bensow R.E. Peng X.M. Ji B. Numerical assessment of cavitation erosion risk on the Delft twisted hydrofoil using a hybrid Eulerian-Lagrangian strategy Int. J. Mech. Sci. 259 2023 108618
13 Wang Z.Y. Cheng H.Y. Ji B. Peng X.X. Numerical investigation of inner structure and its formation mechanism of cloud cavitating flow Int. J. Multiphase Flow 165 2023 104484
14 Wang Z.Y. Cheng H.Y. Ji B. Euler-Lagrange study of cavitating turbulent flow around a hydrofoil Phys. Fluids 33 11 2021 112108
15 Nie S.J. Yi X.N. Zhou H.L. Zhu H.J. Yang L.L. Fu F.L. Li J.Y. Yang H.K. Xu G.X. Lu S. Qiao Y.X. Corrosion behavior of as-cast Al0.75CoFeCr1.25Ni high entropy alloy in 0.5 mol/L NaOH solution J. Iron Steel Res. Int. 2024 10.1007/s42243-024-01180-y
16 Xiao N. Guan X. Wang D. Yan H.L. Cai M.H. Jia N. Zhang Y.D. Esling C. Zhao X. Zuo L. Impact of W alloying on microstructure, mechanical property and corrosion resistance of face-centered cubic high entropy alloys: A review Int. J. Miner. Metall. Mater. 30 9 2023 1667 1679
17 Zhou Y.K. Kang J.J. Jin G. Cui X.F. Zhang J. Ma G.Z. Fu Z.Q. Zhu L.N. She D.S. Yang Y.Y. Effect of vacuum heat treatment on microstructure and corrosion behavior of HVOF sprayed AlCoCrFeNiCu high entropy alloy coatings J. Iron Steel Res. Int. 30 2023 1550 1561
18 Lu Y. Dong Y. Guo S. Jiang L. Kang H. Wang T. Wen B. Wang Z. Jie J. Cao Z. Ruan H. Li T. A promising new class of high-temperature alloys: eutectic high-entropy alloys Sci. Rep. 4 2014 6200 25160691
19 Tsai M.H. Yeh J.W. High-entropy alloys: A critical review Mater. Res. Lett. 2 3 2014 107 123
20 Zhang S. Wu C.L. Zhang C.H. Guan M. Tan J.Z. Laser surface alloying of FeCoCrAlNi high-entropy alloy on 304 stainless steel to enhance corrosion and cavitation erosion resistance Opt. Laser Technol. 84 2016 23 31
21 Wu C.L. Zhang S. Zhang C.H. Zhang H. Dong S.Y. Phase evolution and cavitation erosion-corrosion behavior of FeCoCrAlNiTix high entropy alloy coatings on 304 stainless steel by laser surface alloying J. Alloys Compd. 698 2017 761 770
22 Shang X.L. Wang Z.J. Wu Q.F. Wang J.C. Li J.J. Yu J.K. Effect of Mo addition on corrosion behavior of high-entropy alloys CoCrFeNiMox in aqueous environments Acta Metall. Sin. (eng. Lett.) 32 1 2018 41 51
23 Hsu Y. Chiang W. Wu J. Corrosion behavior of FeCoNiCrCux high-entropy alloys in 3.5% sodium chloride solution Mater. Chem. Phys. 92 1 2005 112 117
24 Yu Y. Xu N.N. Zhu S.Y. Qiao Z.H. Zhang J.B. Yang J. Liu W.M. A novel Cu-doped high entropy alloy with excellent comprehensive performances for marine application J. Mater. Sci. Technol. 69 2021 48 59
25 A, ASTM G32-10, Standard Test Method for Cavitation Erosion Using Vibratory Apparatus, ASTM Int, 2010.
26 Li L. Qiao Y.X. Zhang L.M. Li C.T. Liu Z. Ma R.Y. Yang L.L. Li J.Y. Zheng Y.G. Effects of cavitation erosion-induced surface damage on the corrosion behaviour of TA31 Ti alloy Ultrason. Sonochem. 98 2023 106498
27 Wang Z. Jin J. Zhang G.H. Fan X.H. Zhang L. Effect of temperature on the passive film structure and corrosion performance of CoCrFeMoNi high-entropy alloy Corros. Sci. 208 2022 110661
28 Shun T.T. Chang L.Y. Shiu M.H. Microstructure and mechanical properties of multiprincipal component CoCrFeNiMox alloys Mater. Charact. 70 2012 63 67
29 Xie B.Q. Bao Y.F. Zhong C.H. Song Q.N. Yang K. Jiang Y.F. Cavitation erosion resistance of high-entropy FeCoCrNiMoXB0.2 coatings cladded by laser Surf. Eng. 37 12 2020 1606 1611
30 Kim J.H. Kim S.J. The effect of molybdenum on cavitation erosion and corrosion resistance of Fe-Cr-C-Si hardfacing alloys J. Nucl. Sci. Technol. 45 2014 93 96
31 Xian X. Lin L.J. Zhong Z.H. Zhang C. Chen C. Song K.J. Cheng J.G. Wu Y.C. Precipitation and its strengthening of Cu-rich phase in CrMnFeCoNiCux high-entropy alloys Mater. Sci. Eng. A 713 2018 134 140
32 H.S. Khatak, B. Raj, Corrosion of austenitic stainless steels: mechanism, mitigation and monitoring, Woodhead publishing (2002).
33 Shun T.T. Chang L.Y. Shiu M.H. Age-hardening of the CoCrFeNiMo0.85 high-entropy alloy Mater. Charact. 81 2013 92 96
34 Zhang L.M. Li Z.X. Hu J.X. Ma A.L. Zhang S. Daniel E.F. Umoh A.J. Hu H.X. Zheng Y.G. Understanding the roles of deformation-induced martensite of 304 stainless steel in different stages of cavitation erosion Tribol. Int. 155 2021 106752
35 Ashokkumar M. The characterization of acoustic cavitation bubbles – an overview Ultrason. Sonochem. 18 4 2011 864 872 21172736
36 Qiao Y.X. Wang S. Liu B. Zheng Y.G. Bing L.H. Jiang Z.H. Synergistic effect of corrosionand cavitation erosion of high nitrogen stainless steel Acta Metall. Sin. 52 2016 233 240
37 Kamal K. Ding Y.P. Liu R. Yao J.H. Yao M.X. Corrosion performance of 700 series Stellite alloys in various media J. Mater. Eng. Perform. 28 9 2019 5605 5615
38 Xu L.Y. Li M. Jing H.Y. Han Y.D. Electrochemical Behavior of Corrosion Resistance of X65/Inconel 625 Welded Joints Int. J. Electrochem. Sci. 8 2 2013 2069 2079
39 Gao Z.X. Ji G.J. Shi Z.M. Wang X.H. The tribocorrosion behaviour of YSZ coating deposited on stainless steel substrate in 3.5 wt% NaCl solution Ceram. Int. 47 15 2021 21051 21060
40 Bakhshandeh H.R. Allahkaram S.R. Zabihi A.H. An investigation on cavitation-corrosion behavior of Ni/beta-SiC nanocomposite coatings under ultrasonic field Ultrason. Sonochem. 56 2019 229 239 31101258
41 Li Z.X. Zhang L.M. Ma A.L. Hu J.X. Zhang S. Daniel E.F. Zheng Y.G. Comparative study on the cavitation erosion behavior of two different rolling surfaces on 304 stainless steel Tribol. Int. 159 2021 106994
42 Xia D.H. Ji Y.Y. Zhang R.F. Mao Y.C. Behnamian Y. Hu W.B. Birbilis N. On the localized corrosion of AA5083 in a simulated dynamic seawater/air interface—Part 1: Corrosion initiation mechanism Corros. Sci. 213 2023 110985
43 Chen J.F. Bogaerts W.F. The physical meaning of noise resistance Corros. Sci. 37 11 1995 1839 1842
44 Sanchez-Amaya J.M. Cottis R.A. Botana F.J. Shot noise and statistical parameters for the estimation of corrosion mechanisms Corros. Sci. 47 12 2005 3280 3299
45 Wang C.G. Wu L.P. Xue F. Ma R.Y. Etim I.N. Hao X.H. Dong J.H. Ke W. Electrochemical noise analysis on the pit corrosion susceptibility of biodegradable AZ31 magnesium alloy in four types of simulated body solutions J. Mater. Sci. Technol. 34 10 2018 1876 1884
46 Peng S. Xu J. Li Z.Y. Jiang S.Y. Xie Z.H. Munroe P. Electrochemical noise analysis of cavitation erosion corrosion resistance of NbC nanocrystalline coating in a 3.5.wt% NaCl solution Surf. Coat. Technol. 415 2021 127133
47 Cottis R.A. Interpretation of electrochemical noise data Corrosion 57 3 2001 265 285
48 Cottis R.A. Sources of electrochemical noise in corroding systems Russ. J. Electrochem. 42 2006 497 505
49 Meng F. Liu L. Cui Y. Zhang T. Li Y. Wang F. A novel design of electrochemical noise configuration based on embedded-electrodes for in-situ evaluation of epoxy coating under marine alternating hydrostatic pressure Prog. Org. Coat. 131 2019 346 356
50 Aballe A. Bethencourt M. Botana F.J. Marcos M. Using wavelets transform in the analysis of electrochemical noise data Electrochim. Acta 44 26 1999 4805 4816
51 Aballe A. Bethencourt M. Botana F.J. Marcos M. Wavelet transform-based analysis for electrochemical noise Electrochem. Commun. 1 7 1999 266 270
52 J. Li, C.W. Du, Z.Y. Liu, X.G. Li, M. Liu, Effect of microstructure on the corrosion resistance of 2205 duplex stainless steel. Part 2: Electrochemical noise analysis of corrosion behaviors of different microstructures based on wavelet transform, Constr. Build. Mater. 189 (2018) 1294–1302 111512.
53 Ye Z.X. Guan L. Li Y. Zhong J.X. Liao L.C. Xia D.W. Huang J.Y. Understanding the galvanic corrosion of Cu-Ni alloy/2205 DSS couple using electrochemical noise and microelectrochemical studies Corros. Sci. 224 2023 111512
54 Li L. Cai S.S. Wang X.J. Ma R.Y. Amin M.A. Thabet H.K. Alshahrani W.A. Qiao Y.X. Cao F.T. Zhang J.H. Cai C. Yuan X.H. Electrochemical noise analysis of corrosion sensitivity of Pb-free solders in 5 wt% citric acid solution Adv. Compos. Hybrid Mater. 7 2024 24
55 Xia D.H. Song S.Z. Behnamian Y. Detection of corrosion degradation using electrochemical noise (EN): Review of signal processing methods for identifying corrosion forms Corros. Eng. Sci. Technol. 51 7 2016 527 544
56 Eftekhari S. Shooshtari Gugtapeh H. Rezaei M. Effect of meat extract as an eco-friendly inhibitor on corrosion behavior of mild steel: Electrochemical noise analysis based on shot noise and stochastic theory Const. Build. Mater. 292 2021 123423
57 Zhang L.M. Ma A.L. Yu H. Umoh A.J. Zheng Y.G. Correlation of microstructure with cavitation erosion behaviour of a nickel-aluminum bronze in simulated seawater Tribol. Int. 136 2019 250 258
58 J. Basumatary, R.J.K. Wood, Synergistic effects of cavitation erosion and corrosion for nickel aluminium bronze with oxide film in 3.5% NaCl solution, Wear 376–377 (2017) 1286–1297.
59 Guo H.X. Lu B.T. Luo J.L. Non-Faraday material loss in flowing corrosive solution Electrochim. Acta 51 25 2006 5341 5348
60 Tian Y. Zhao H. Yang R. Zhang H.J. Yu M. Zhou P. Li H. Chen X.Y. Behavior of the hard phases of copper alloys subjected to cavitation erosion investigated by SEM observation Tribol. Int. 174 2022 107771
61 Niebuhr D. Cavitation erosion behavior of ceramics in aqueous solutions Wear 263 1–6 2007 295 300
62 Zhang X.B. Liu C.S. Liu X.D. Dong J. Yu B. Cavitation erosion behavior of WC coatings on CrNiMo stainless steel by laser alloying Int. J. Miner. Metall. Mater. 16 2 2009 203 207
63 Hou G.L. Zhao X.Q. Zhou H.D. Lu J.J. An Y.L. Chen J.M. Yang J. Cavitation erosion of several oxy-fuel sprayed coatings tested in deionized water and artificial seawater Wear 311 1–2 2014 81 92
64 Song Q.N. Li H.L. Zhang H.N. Hong H. Xu N. Zhang G.Y. Bao Y.F. Qiao Y.X. Correlation between microstructure and corrosion and cavitation erosion behaviors of nickel aluminum bronze Trans. Nonferrous Met. Soc. China 32 9 2022 2948 2964
65 Paolantonio M. Hanke S. Damage mechanisms in cavitation erosion of nitrogen-containing austenitic steels in 3.5% NaCl solution Wear 464 2021 203526
66 Qin Z.B. Li X.H. Xia D.H. Zhang Y. Feng C. Wu Z. Hu W.B. Effect of compressive stress on cavitation erosion-corrosion behavior of nickel-aluminum bronze alloy Ultrason. Sonochem. 89 2022 106143
67 Bao Y.F. Guo L.P. Zhong C.H. Song Q.N. Yang K. Jiang Y.F. Wang Z.R. Effects of WC on the cavitation erosion resistance of FeCoCrNiB0.2 high entropy alloy coating prepared by laser cladding Mater. Today Commun. 26 2021 102154
68 Liu J. Chen T.Z. Yuan C.Q. Bai X.Q. Performance analysis of cavitation erosion resistance and corrosion behavior of HVOF-Sprayed WC-10Co-4Cr, WC-12Co, and Cr3C2-NiCr coatings J. Therm Spray Technol 29 4 2020 798 810
69 Ding X. Cheng X.D. Yu X. Li C. Yuan C.Q. Ding Z.X. Structure and cavitation erosion behavior of HVOF sprayed multi-dimensional WC–10Co4Cr coating Trans. Nonferrous Met. Soc. China 28 3 2018 487 494
70 Kwok C.T. Cheng F.T. Man H.C. Synergistic effect of cavitation erosion and corrosion of various engineering alloys in 3.5% NaCl solution Mater. Sci. Eng. A 290 1–2 2000 145 154
71 Wang Y. Yin Y.Y. Wu G.L. Li L. Yao J.H. Zhang Q.L. The microstructure and cavitation erosion resistance of Ti6Al4V alloy treated by laser gas nitriding with scanning galvanometer Opt. Laser. Technol. 153 2022 108270
72 Li Z.M. Pradeep K.G. Deng Y. Raabe D. Tasan C.C. Metastable high-entropy dual-phase alloys overcome the strength–ductility trade-off Nature 534 7606 2016 227 230 27279217
