Applications of High-Pressure Technology for High-Entropy Alloys: A Review

Abstract

High-entropy alloys are a new type of material developed in recent years. It breaks the traditional alloy-design conventions and has many excellent properties. High-pressure treatment is an effective means to change the structures and properties of metal materials. The pressure can effectively vary the distance and interaction between molecules or atoms, so as to change the bonding mode, and form high-pressure phases. These new material states often have different structures and characteristics, compared to untreated metal materials. At present, high-pressure technology is an effective method to prepare alloys with unique properties, and there are many techniques that can achieve high pressures. The most commonly used methods include high-pressure torsion, large cavity presses and diamond-anvil-cell presses. The materials show many unique properties under high pressures which do not exist under normal conditions, providing a new approach for the in-depth study of materials. In this paper, high-pressure (HP) technologies applied to high-entropy alloys (HEAs) are reviewed, and some possible ways to develop good properties of HEAs using HP as fabrication are introduced. Moreover, the studies of HEAs under high pressures are summarized, in order to deepen the basic understanding of HEAs under high pressures, which provides the theoretical basis for the application of high-entropy alloys.Metals 2019, 9, 867 2 of 16 with the development of human civilization. However, due to the limitations of technical conditions, the application of pressure has just begun. High-pressure technology is a relatively-young and emerging discipline, but most of the condensed matter in the universe is under high pressure. The research on high pressures relies heavily on the experimental techniques, and each progression of the method has led to a significant expansion of our basic understanding of material behavior under high pressures.The progress in high-pressure experimental technology has directly promoted the development of the high-pressure science and provided an advanced method for frontier subjects. It has become an important field in modern scientific research. There are few studies on the structures of HEAs under high pressures. Interactions within the materials will change under high pressures and induce the generation of high-pressure phase transitions, thus becoming a new material with special properties. The materials will show many unique properties under high pressures, ones which do not exist under normal conditions, providing a subject for the in-depth study of materials. The behavior of HEAs under high pressures is a potential research direction for the future. High-Entropy Alloys (HEAs) ConceptHEAs are kinds of alloys developed in recent years. HEAs are loosely defined as solid-solution alloys that contain more than five principal elements in an equal or near-equal atomic percent (at. %) [4]. These kinds of alloys were defined by Yeh et al. [4] in 2004 as HEAs, and in the same year named by Cantor [5] et al. as the multi...

Recent Advances in Additive Manufacturing of High Entropy Alloys and Their Nuclear and Wear-Resistant Applications

“…These changes often convert the microstructures and affect the mechanical and structural properties. Dong et al [56] reviewed the applications of high pressure technology for HEAs. They reviewed the use of dynamic high pressure, diamond anvil cells, high pressure torsion and hexahedron anvil press.…”

“…As research on the properties of HEAs progressed, various research groups reviewed the mechanical performances [40][41][42], heat resistance [43,44], magnetic [45] and physical properties of HEAs [46,47]. As synthesis techniques for HEAs advanced, various reviews on simulations and modeling [48,49], fabrication methods [50,51], welding techniques [52][53][54][55], high pressure technology [56] were published. Due to the possibility of having a wide composition range, new HEAs and their properties were reported continuously beyond the existing literature.…”

Complex Concentrated Alloys (CCAs)—Current Understanding and Future Opportunities

“…Eight research articles, four reviews, and one perspective have been published in this special issue of Metals. The subjects are multidisciplinary and divided into several topics including: (i) simulation and modeling for predicting structure and properties [1], (ii) unique deformation mechanisms in multi-principal alloys [2][3][4], (iii) microstructure and properties resulting from various processing routes [5][6][7][8][9][10], (iv) corrosion and surface degradation behavior [11,12], and (v) perspectives on ways to design mechanically and functionally advanced concentrated alloys [13]. Beyramali Kivy et al [1] reviewed the computational tools for studying the structure and properties of multi-principal alloys and identified the advantages as well as limitations of simulations in accelerating design and development of new alloys.…”

“…The processing-microstructure-properties relationship in complex concentrated alloys are discussed in one review article and five research papers in this special issue [5][6][7][8][9][10]. Dong et al [5] reviewed the structure, evolution in properties, and deformation behavior of HEAs after high-pressure treatment (HPT).…”

“…The processing-microstructure-properties relationship in complex concentrated alloys are discussed in one review article and five research papers in this special issue [5][6][7][8][9][10]. Dong et al [5] reviewed the structure, evolution in properties, and deformation behavior of HEAs after high-pressure treatment (HPT). A certain group of concentrated alloys showed phase transformation under high pressure while others remained stable, which indicates unique structural changes and phase transitions in complex concentrated alloys (CCAs) under high pressure.…”