High entropy alloys12/15/2023 High-entropy alloys (HEAs) are a class of alloys that can exhibit promising properties including enhanced irradi-ation resistance, high-temperature strength, and corrosion resistance. Here, we review work on some of the most damage-tolerant HEAs discovered to date and discuss the fundamental reasons why their resistance to fracture and subsequent stable crack growth is so exceptional. While significant efforts have been put into rapid screening and narrowing the compositional space of HEAs to a manageable scope, there more » are still only a few metallic alloys that push the limits of mechanical performance. The main reason for this is that some face-centered-cubic alloy compositions have been shown to exhibit truly outstanding mechanical properties with extraordinary combinations of strength, ductility, and fracture toughness, particularly at cryogenic temperatures, whereas certain body-centered-cubic refractory compositions display remarkable high-temperature strength. « lessĪbstract Since the concept of high-entropy alloys (HEAs) as materials with at least four or five principal elements in (near)-equiatomic composition was introduced in 2004, this new class of materials has penetrated essentially all materials science-related fields. The decreased corrosion resistance is revealed to be directly related to the constituents of passivated films. The results show that the Al x(CoCrFeNi) 100-x HEA thin films possess outstanding corrosion-resistant properties, but the resistance diminishes with the increasing Al content. Complementary X-ray photoelectron spectroscopy analysis reveals the compositional variation of passivated films formed on the sample surface after immersion. Corrosion characteristics of combinatorial samples immersed in the 3.5 wt% (wt%) NaCl solution are more » evaluated via electrochemical tests. Both the FCC and BCC thin films demonstrate a uniform elemental distribution. With the increased amount of Al, crystal-structures of thin films transform from face-centered cubic (FCC) to body-centered cubic (BCC). The effects of Al on the microstructure and corrosion behavior are investigated. In the present study, high-throughput synthesis of an Al x(CoCrFeNi) 100-x combinatorial material library covering x = 4.5–40 atomic percent Al is achieved, using magnetron cosputtering. High-entropy alloys (HEAs) are inherently complex and potentially span a vast composition space, making their research and discovery challenging. Finally, we also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be = , Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. In this paper, we review recent progress in understanding the salient features of high-entropy alloys. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. Typically, it involves the addition of relatively small amounts of secondary elements to a primary element. We present that alloying has long been used to confer desirable properties to materials.
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