A Promising New Class of High-Temperature Alloys: Eutectic High-Entropy Alloys

Abstract

High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700°C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility.

Science and technology in high-entropy alloys

“…The FCC alloy of Al x CoCrFeNiMn system exhibits excellent plasticity and low strength, whereas the dual phase alloys exhibit a better combination of strength and ductility. The AlCoCrFeNi 2.1 alloy with dual phases also presents promising tensile properties with an elongation and fracture strength of 23% and 1,200 MPa, respectively [88].…”

Al-Ti-Containing Lightweight High-Entropy Alloys for Intermediate Temperature Applications

“…Recently, high-entropy alloys (HEAs) have attracted considerable attention because of their extraordinary properties [1][2][3][4][5][6][7][8][9][10], and numerous HEAs have been reported with various compositions [1][2][3][4][5][6][7][8][9][10]. Three major HEAs are CoCrFeMnNi alloy which has potential applications in cryogenic environments [5,6], refractory VNbMoTaW alloy for high-temperature structural applications [7,8], and AlCoCrFeNi alloy which maintains high strength up to intermediate temperatures [9,10].…”

“…Three major HEAs are CoCrFeMnNi alloy which has potential applications in cryogenic environments [5,6], refractory VNbMoTaW alloy for high-temperature structural applications [7,8], and AlCoCrFeNi alloy which maintains high strength up to intermediate temperatures [9,10]. AlCoCrFeNi HEA is relatively lightweight and has excellent specific strength around intermediate temperatures.…”

“…AlCoCrFeNi HEA is relatively lightweight and has excellent specific strength around intermediate temperatures. It is a possible alternative for Ti alloys or wrought superalloys such as Inconel 718 [9,10]. Additional weight reduction can improve the competitiveness of the lightweight HEAs; therefore, we attempted to develop new HEAs that contain lightweight elements, namely Al and Ti.…”

Colossal dielectric constant in high entropy oxides

“…Gludovatz et al, Science 345, 1153 (2014) [6] and Lu et al, Sci. Rep. 4, 6200 (2014) [7], but also electrical properties, Kozelj et [10]. Many unexplored compositions and properties still remain for this class of materials due to their large phase space.…”