Multicomponent and High Entropy Alloys

Abstract

This paper describes some underlying principles of multicomponent and high entropy alloys, and gives some examples of these materials. Different types of multicomponent alloy and different methods of accessing multicomponent phase space are discussed. The alloys were manufactured by conventional and high speed solidification techniques, and their macroscopic, microscopic and nanoscale structures were studied by optical, X-ray and electron microscope methods. They exhibit a variety of amorphous, quasicrystalline, dendritic and eutectic structures.Keywords: alloying strategy; amorphous alloys; fcc single phase; Gibbs phase rule; high entropy alloys; icosahedral phase; multicomponent alloys; quasicrystals; solid solubility Multicomponent Alloys Alloying StrategiesThe conventional way of developing a new material is to select the main component based upon some primary property requirement, and to use alloying additions to confer secondary properties. This strategy has led to many successful multicomponent materials with a good balance of engineering properties. Typical examples include high-temperature nickel superalloys and corrosion-resistant stainless steels. In some cases two principal components are used, such as in copper-zinc brasses or alumino-silicate refractories.Cantor [1] was the first to point out that this kind of conventional alloying strategy leads to an enormous amount of knowledge about materials based on one or sometimes two components, but little or no knowledge about materials containing several main components in approximately equal proportions. Information and understanding about alloys close to the corners and edges of a OPEN ACCESS

High-entropy alloys: a critical assessment of their founding principles and future prospects

“…However, a number of potential applications have been highlighted in the literature. These include their use as protective coatings owing to their good corrosion and wear resistance 1,80,84,115,170,171,[219][220][221][222][223][224][225][226][227][228][229][230][231] (see review of laser-deposited HEA coatings by Zhang et al 232 ), as alloys for bulk metallic glasses, 11,[233][234][235][236] and even as materials for hydrogen storage 237 and diffusion barriers. 1,181,182 There has also been interest in their magnetic 1,10,97,[238][239][240][241][242][243] and thermoelectric properties.…”

“…1, and a number of reviews of the HEA literature have been made over the past 5 years. 5,6,8,[10][11][12][13] These have been in the form of comprehensive and detailed summaries, such as the review by Zhang et al, 14 as well as shorter critical assessments, such as the recent work of Miracle. 15 However, none of these have critically assessed the evidence for the four core effects described above -this is one, and the most important, of the three key aims of this review, and is tackled to begin with.…”

X-ray Diffraction and EBSD Study of Al-Ti-Co-Ni-Fe High-Entropy Alloy

“…These alloys, in contrast to the conventional, have properties that do not result directly from the synergistic interaction of individual elements [2]. Each element can be located in any lattice position with equal probability, furthermore the simple crystallographic structures like fcc, bcc, or duplex of these are created instead of complex structures [3,4].…”

Effect of Heat Treatment on the Microstructure, Phase Distribution, and Mechanical Properties of AlCoCuFeMnNi High Entropy Alloy

“…According to conventional strategy for developing new alloy systems, multiprincipal elements can lead to the formation of intermetallic compounds and complex microstructures. Yeh et al [1] and Cantor [2] have broken this thinking pattern with the development of high entropy alloys (HEA). High entropy alloys are the systems with usually more than five principle elements at levels of 5-35 at % [3][4][5].…”