Alloying and Processing Effects on the Aqueous Corrosion Behavior of High-Entropy Alloys

Abstract

Abstract:The effects of metallurgical factors on the aqueous corrosion behavior of highentropy alloys (HEAs) are reviewed in this article. Alloying (e.g., Al and Cu) and processing (e.g., heat treatments) effects on the aqueous corrosion behavior of HEAs, including passive film formation, galvanic corrosion, and pitting corrosion, are discussed in detail. Corrosion rates of HEAs are calculated using electrochemical measurements and the weight-loss method. Available experimental corrosion data of HEAs in two common solutions [sulfuric acid (0.5 M H 2 SO 4 ) and salt water (3.5 weight percent, wt.%, NaCl)], such as the corrosion potential (E corr ), corrosion current density (i corr ), pitting potential (E pit ), and passive region (ΔE), are summarized and compared with conventional corrosionresistant alloys. Possible directions of future work on the corrosion behavior of HEAs are suggested.

Deviation from high-entropy configurations in the atomic distributions of a multi-principal-element alloy

“…A greater reduction occurs, however, due to the CSRO, which may originate from the preferred nearest-neighbour pairing in the liquid. Equation (19) was used to calculate the CSRO entropy reduction, corresponding to the case of strongly enhanced Al-TM pairs (Z Al ¼ 1, The room temperature neutron PDF data (blue), and the calculated 43 PDF results (red), based on the expected cubic crystal structure, that is, the atomic distances, defined by the unit cell and long-range lattice periodicity, agree reasonably well at large distances, r. As shown by the difference curve (green), and highlighted by the dashed rectangle, the agreement below 10 Å is less than that at larger distances. This trend is consistent with the expectation that HEAs are locally strained 24 .…”

“…Many multi-principal-element alloys have shown exceptional properties, including high strengths at elevated temperatures 6,8,[10][11][12][13][14][15] , ductility 16,17 , toughness 18 , resistance to corrosion 19,20 , wear 21 and fatigue 22 . These favourable properties are sometimes associated with the locally strained solid solution structures, especially those with simple, single-phase microstructures 5,23,24 .…”

Microstructure, Mechanical and Corrosion Behaviors of CoCrFeNiAl0.3 High Entropy Alloy (HEA) Films

“…In addition to its mechanical properties, corrosion-resistance is another important factor that needs to be considered for practical applications of HEA. Thus, this has also been extensively studied [26][27][28]. Nevertheless, the corrosion performance of HEA coatings synthesized via sputtering has not yet been widely reported.…”

Influence of Annealing on the Microstructures and Oxidation Behaviors of Al8(CoCrFeNi)92, Al15(CoCrFeNi)85, and Al30(CoCrFeNi)70 High-Entropy Alloys

“…It is well-known that these alloys typically form phases with simple FCC, BCC, and HCP crystal structures and can contain ordered intermetallic phases [4]. HEAs also exhibit the inherent potential to be alloyed with high concentrations of Al and/or Cr to promote enhanced oxidation resistances without necessarily forming various intermetallic phases that can be deleterious to strength [5][6][7]. In addition, HEAs have been reported to exhibit sluggish diffusion kinetics [8][9][10] and high thermal stabilities [11][12][13], making them ideal candidates for use in high temperature applications.…”

“…Senkov et al [26] examined the 1000 • C oxidation behavior of an arc-melted NbCrMo 0.5 Ta 0. 5 TiZr HEA. The oxidation behavior was reported to be superior to that of similar Nb-based refractory alloys, with an oxide consisting of a combination of NbCrO 4 , TiO 2 , and Cr 2 O 3 .…”