Hydrogen enhances strength and ductility of an equiatomic high-entropy alloy

Abstract

Metals are key materials for modern manufacturing and infrastructures as well as transpot and energy solutions owing to their strength and formability. These properties can severely deteriorate when they contain hydrogen, leading to unpredictable failure, an effect called hydrogen embrittlement. Here we report that hydrogen in an equiatomic CoCrFeMnNi high-entropy alloy (HEA) leads not to catastrophic weakening, but instead increases both, its strength and ductility. While HEAs originally aimed at entropy-driven phase stabilization, hydrogen blending acts opposite as it reduces phase stability. This effect, quantified by the alloy’s stacking fault energy, enables nanotwinning which increases the material’s work-hardening. These results turn a bane into a boon: hydrogen does not generally act as a harmful impurity, but can be utilized for tuning beneficial hardening mechanisms. This opens new pathways for the design of strong, ductile, and hydrogen tolerant materials.

Strong and Ductile Non-equiatomic High-Entropy Alloys: Design, Processing, Microstructure, and Mechanical Properties

“…2. For the widely studied transition-metal HEAs with their good strength-ductility combinations, other properties such as the resistance to hydrogen-induced degradation, 28,29 corrosion resistance, fatigue behavior, and magnetic performance can also be explored in an effort to find superior combinations of properties, i.e., multifunctionalities, to justify their relatively high cost compared with established high-strength and austenitic stainless steels. Also, following the design approach associated with the stacking fault energies and/or the free energies, a shape-memory effect could be introduced into non-equiatomic HEAs.…”

Strategies for improving the sustainability of structural metals

“…Examples over the millennia have been agricultural tools, manufacturing machinery, energy conversion engines and reinforcements in huge concrete-based infrastructures. Recent applications include structural alloys for weight reduction combined with high strength and toughness in the transportation sector [1][2][3][4] , efficient turbines operating at higher temperatures for power plants and air traffic 5,6 , components for safe nuclear and fusion power and disposal 7 , targeted endurance or corrosive dissolution of biomedical implants 8 , embrittlement-resistant infrastructures for hydrogen-based industries 9 or reusable spacecraft 10 . Metallurgical alloys and products boost innovation and economic growth: the global market for metals is about 3,000 billion euros per year 11,12 .…”

Impact of interstitial C on phase stability and stacking-fault energy of the CrMnFeCoNi high-entropy alloy

“…The equiatomic CrMnFeCoNi alloy, also termed as the Cantor alloy [1], shows a remarkable combination of strength and ductility [2][3][4][5]. Their impressive mechanical properties could be further enhanced by modifying the compositions away from equiatomic CrMnFeCoNi [6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”