Hydrogen‐assisted fatigue crack propagation behavior of equiatomic Co–Cr–Fe–Mn–Ni high‐entropy alloy

Abstract

The equiatomic Co-Cr-Fe-Mn-Ni high-entropy alloy (HEA) shows well hydrogen embrittlement resistance under monotonic tensile load. However, the fracture behavior under cyclic load is still unclear. In this study, combining with the fracture features analysis by electron back-scattered diffraction and electron channeling contrast imaging techniques, the hydrogen-assisted fatigue crack propagation behavior of equiatomic Co-Cr-Fe-Mn-Ni HEA under in situ electrochemical hydrogen charging was investigated. The results suggest that the hydrogen had significant accelerating effects on the fatigue crack growth rate of Co-Cr-Fe-Mn-Ni HEA. Intergranular cracking with the formation of dislocation cells was observed at low stress intensity range (ΔK) area, while transgranular cracking with deformation twins was observed at a high ΔK area. The formation of these deformation features was assisted by hydrogen-assisted dislocation emission.

As-Cast Microstructures of High Entropy Alloys Designed to Be TaC-Strengthened

“…Beside the conventional foundry of equimolar FeCoNiCrMn alloys, different ways of elaboration of superalloys were recently applied to HEAs: single crystalline growth [8] , additive manufacturing [9] or thin film deposition [10] . Their behaviors in case of extreme conditions of solicitations were also explored, mechanical properties [11,12] or chemical reactivity at high temperature [13] . Evolutions of chemical composition -variation of the Co or Ni content [14] (and even suppression of Co [15] or of Ni [16] ) -were tested, and the notion of "Medium Entropy Alloys" has also appeared [17] .…”

The Study on Fatigue Crack Growth Rate of 4130X Material under Different Hydrogen Corrosion Conditions

“…It has been shown that the existence of hydrogen can lead to hydrogen embrittlement [ 3 ] and reduce the fracture toughness of materials [ 4 ]. Hence, the fatigue crack growth rate of metal in hydrogen is much higher than that in the air [ 5 , 6 ]. The hydrogen sulfide contained in natural gas may act as a “toxic agent”, which makes the hydrogen atoms precipitated by the cathode reaction difficult to combine into hydrogen molecules to escape, so hydrogen is enriched on the surface of the steel and forms hydrogen diffusion [ 7 , 8 , 9 ], which causes great damage to the steel.…”

Characterization and corrosion evaluation of high‐entropy TixNb0.5MnMo0.5Zr0.3 (x = 0.5, 0.75, 1) thin films for biomedical applications

“…In the current work, the fabrication and characterization of novel Ti x Nb 0.5 MnMo 0.5 Zr 0.3 (x = 0.5, 0.75, 1) HEA thin films deposited on the AISI 316L austenitic stainless steel were studied. Although several studies have focused on the mechanical performance of HEAs, [14,32,33] investigations of the corrosion properties of HEA thin films for biological applications are still limited. This study focuses on the investigation of the role of the Ti content on the microstructure and electrochemical behavior of the mentioned HEA thin films.…”