Effect of Aluminum Content on Plasma-Nitrided Al x CoCrCuFeNi High-Entropy Alloys

Abstract

High-entropy alloys (HEAs) Al x CoCrCuFeNi with different aluminum contents (x = 0 to 1.8) were plasma nitrided at 525°C for 45 hours with an aim to develop wear-resistant structural parts. The nitrided layer comprises a well-nitrided dendrite phase and an un-nitrided Cu-rich interdendrite phase. Surface hardening is a result of the formation of various nitrides in the nitrided dendrite: CrN, Fe 4 N, and AlN. With increasing aluminum content, the hardness of the nitrided layer increases due to the increased amount of hard AlN phase and the increased volume fraction of bcc phase being harder than the fcc one. The nitrided layer thickness shows an apparent decrease with the increasing aluminum content of the alloy. The present alloy system provides a wide range of substrate hardness from Hv 170 to 560 before nitriding, which even becomes harder by around Hv 30 after nitriding. For Al 0.5 CoCrCuFeNi alloy having the highest surface hardness of Hv 1300, a layer thickness of 23 lm, and a substrate hardness of Hv 300, an adhesive wear test confirms its superior wear resistance as being 17 times that of the un-nitrided samples.

Electrical, magnetic, and Hall properties of AlxCoCrFeNi high-entropy alloys

“…Studies [4,14] have shown that Al is a strong BCC former and can promote atomic bonding in high-entropy alloys (HEAs). Therefore, the mechanical property [15], wear behavior [16], and anti-corrosion ability [17] are closely related to the Al content.…”

High-Entropy Alloys: A Critical Review

“…[122][123][124] Non-metallic elements such as C, B, and N can also be incorporated to achieve even higher strength. [14,99,100,125,126] Additionally, HEAs can also be prepared by other process and/or in other forms. For example, HEAs can be processed by a wrought process including homogenization, hot/cold working, and annealing [62,64] to eliminate casting defects and improve microstructure.…”

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

“…3,21,[61][62][63][64][65][66][67][68][69][70][71][72][73][74] Part of the Al x CrFeCoNiCu series of alloys, which have received a great deal of attention, 1,64,73,[75][76][77][78][79][80][81][82][83][84][85][86] initial reports appeared to suggest that Al 0.5 CrFeCoNiCu was stable as a single face-centred cubic ( fcc) solid-solution phase. 3,[62][63][64]75,76,78 Subsequent studies, however, found that this not the case, and have 17,31,35,62,69,73,[85][86][87]97,107,113,125,…”