Effect of Microstructure on Wear and Corrosion Performance of Thermally Sprayed AlCoCrFeMo High‐Entropy Alloy Coatings

Abstract

mixed in equimolar or close to equimolar concentrations, enabling them to form a single-phase solid solution. [4] However, the formation of intermetallics together with solid solution phases was also reported for the HEAs. [5,6] The alloys exhibit an inherently high configurational entropy effect owing to compositionally complex mixing, which promotes the solid solution phases in the form of face-centered cubic (FCC) and/or body-centered cubic (BCC) phases. [6] Other core effects, such as sluggish diffusion, distorted lattice, and cocktail effect, favor HEAs to have outstanding properties, including excellent strength, [7] significant toughness, [8] and better strain hardening ability [9] with remarkable tribological characteristics, including superior wear and corrosion resistance. [6,[9][10][11] Various studies had been employed to produce HEAs by arc melting, [12,13] spark plasma sintering, [14] laser technology, [15] microwave processing, [5,16] additive manufacturing, [17,18] and thermal spraying. [19,20] Among the techniques, thermal spray manufacturing is a promising and well-established technology, which is capable of using a broad range of feedstocks (including alloys, ceramics, and polymers) for producing thick coatings for use in developing protective surface layers. [21] The impact of thermal spraying of HEA coatings on microstructure, mechanical, and wear properties has been studied previously. [22,23] For instance, Wang et al. [24] reported excellent hardness for the AlCoCrFeNi HEA coatings developed via atmospheric plasma spraying due to hard BCC and ordered B2 phases. Another study by Meghwal et al. [22] reported high hardness of around 4 GPa for AlCoCrFeNi due to the formation of Al-rich oxide phases. Still a noticeable decrease in the corrosion performance was found compared to 316L stainless steel under seawater conditions. However, the high-temperature heat source in thermal spraying can result in undesirable phase transformations, residual stresses, and oxide contaminations. [23] In addition, the oxide inclusions along with voids such as pores and cracks are detrimental for protective performance against electrochemical damage. To probe such microstructural inhomogeneities, deposition techniques that operate with low-temperature heat sources are desirable.Cold spraying is a branch of thermal spray technologies that received attention for structural repair coatings for various

Data mining accelerated the design strategy of high‐entropy alloys with the largest hardness based on genetic algorithm optimization

“…The microstructure of HEA Al 18 Co 21 Cr 23 Fe 23 Mo 15 is characterized as polycrystalline, featuring micron‐scale white acicular precipitates at the grain boundary and a minor amount of the white phase distributed within the crystal. EDS mappings reveal a notable concentration of Mo in the white acicular precipitates, aligning with literature that identifies Mo as a primary constituent of the σ phase [83,84] . The regular banded structure observed in the crystal is termed a modulated microstructure, commonly described in various studies as a eutectic arrangement comprising BCC and B2 phases [85,86] .…”

RETRACTED ARTICLE: Microstructure and wear behaviour of AlCoCrFeNi-coated SS316L by atmospheric plasma spray process

“…This eventually reduces the intensity of abrasive and adhesive wear which in turn reduces the SWR of the coating. The trend also reveals a gradual increase in the COF, and it decreases gradually due to the formation of MML along the surface, which acts as a protective barrier [ 58 ]. The COF of coated and annealed samples was 10.94% and 38.82% better than the coated and uncoated sample before annealing.…”

Thermal spray coatings: For industrial and biomedical applications

“…The analysis signifies that the high-entropy alloys, nanostructure coatings, multilayer approaches and hybrid thermal spray techniques are examples of advanced coatings that have developed significantly. [164][165][166] There have been several reports of advancements in resistance to wear, corrosion resistance, thermal resistance, and coating retention, especially with optimizing process methods like APS, HVAF, HVOF, plasma spraying and cold spray. [167][168][169][170][171][172][173] The relative performance of the main thermal spray processes across important coating characteristics is shown in a bar chart to give a better comparative analysis of these technological developments as shown in Figure 10.…”

“…The analysis signifies that the high-entropy alloys, nanostructure coatings, multilayer approaches and hybrid thermal spray techniques are examples of advanced coatings that have developed significantly. 164–166 There have been several reports of advancements in resistance to wear, corrosion resistance, thermal resistance, and coating retention, especially with optimizing process methods like APS, HVAF, HVOF, plasma spraying and cold spray. 167–173…”