“…Vacancy formation and clustering induce a long-range internal strain which reduces apparent elastic stiffness coefficients to a greater extent than hydrogen self-stress. Consequently, the softening behavior observed for short-range interactions in dislocations can be directly related to the point defects and clusters of vacancies produced during the initial incorporation of hydrogen, as confirmed by TEM observations 11,45 and our present measurement (around 3.8 10 −4 V/Ni for the unstrained sample after a hydrogen pre-charging to 7 wppm compared with 2.8 10 −24 V/Ni at P H2 = 1 bar and 300 K for pure nickel single crystals 46 ). This interpretation is mainly based on the hypothesis that vacancy concentration does not change during strengthening, which is not the case, as previously shown 47,48 .…”
Section: Resultsmentioning
confidence: 57%
“…Expressed differently, these results show a softening effect on the athermal components of stress (τ X and τ eff ≈τ µ in accordance with the fact that τ* represents only 10% of the short-range interactions). The hydrogen softening process observed on the short-range interactions with mobile dislocations (τ eff ) could be related to the shielding mechanism in which hydrogen reduces elastic pair interactions between two dislocations 6–11 .Figure 3Effective stress ( a ) and back stress ( b ) as a function of shear strain for Ni and Ni-H.…”
Section: Resultsmentioning
confidence: 99%
“…Recent investigations into the impact of hydrogen on elastic properties (E, μ the Young modulus and shear modulus, respectively) demonstrated that point defects produced by the incorporation of hydrogen had a higher impact on the elastic constant than the solute 6–11 . The decrease in elastic properties with the addition of hydrogen has been well documented recently in the superabundant vacancies (SAV) mechanism 11 . Vacancy formation and clustering induce a long-range internal strain which reduces apparent elastic stiffness coefficients to a greater extent than hydrogen self-stress.…”
Section: Resultsmentioning
confidence: 99%
“…By extending the linear-elastic theory of the equilibrium between interstitial solid solution atoms and host metal lattices used in several studies 6–10 , we have recently determined the degradation of elastic properties as a function of hydrogen alone, monovacancies and vacancy cluster concentrations using an analytical approach verified by DFT calculations 11 . This degradation is due more to vacancy clusters than hydrogen itself 11 .…”
Hydrogen-deformation interactions and their role in plasticity are well accepted as key features in understanding hydrogen embrittlement. In order to understand the nature of the hydrogen-induced softening process in f.c.c. metals, a substantial effort was made in this study to determine the effect of hydrogen on the tensile stress-strain behavior of nickel single crystal oriented for multiple-slips. It was clearly established that the hydrogen softening process was the result of a shielding of the elastic interactions at different scales. Hydrogen-induced softening was then formalized by a screening factor S of 0.8 ± 0.05 for 7 wppm of hydrogen, which can be incorporated into standard dislocation theory processes. The amplitude of softening suggests that the shielding process is mainly responsible for the stress softening through the formation of vacancy clusters, rather than a direct impact of hydrogen. This effect is expected to be of major importance when revisiting the impact of hydrogen on the processes causing damage to the structural alloys used in engineering.
“…Vacancy formation and clustering induce a long-range internal strain which reduces apparent elastic stiffness coefficients to a greater extent than hydrogen self-stress. Consequently, the softening behavior observed for short-range interactions in dislocations can be directly related to the point defects and clusters of vacancies produced during the initial incorporation of hydrogen, as confirmed by TEM observations 11,45 and our present measurement (around 3.8 10 −4 V/Ni for the unstrained sample after a hydrogen pre-charging to 7 wppm compared with 2.8 10 −24 V/Ni at P H2 = 1 bar and 300 K for pure nickel single crystals 46 ). This interpretation is mainly based on the hypothesis that vacancy concentration does not change during strengthening, which is not the case, as previously shown 47,48 .…”
Section: Resultsmentioning
confidence: 57%
“…Expressed differently, these results show a softening effect on the athermal components of stress (τ X and τ eff ≈τ µ in accordance with the fact that τ* represents only 10% of the short-range interactions). The hydrogen softening process observed on the short-range interactions with mobile dislocations (τ eff ) could be related to the shielding mechanism in which hydrogen reduces elastic pair interactions between two dislocations 6–11 .Figure 3Effective stress ( a ) and back stress ( b ) as a function of shear strain for Ni and Ni-H.…”
Section: Resultsmentioning
confidence: 99%
“…Recent investigations into the impact of hydrogen on elastic properties (E, μ the Young modulus and shear modulus, respectively) demonstrated that point defects produced by the incorporation of hydrogen had a higher impact on the elastic constant than the solute 6–11 . The decrease in elastic properties with the addition of hydrogen has been well documented recently in the superabundant vacancies (SAV) mechanism 11 . Vacancy formation and clustering induce a long-range internal strain which reduces apparent elastic stiffness coefficients to a greater extent than hydrogen self-stress.…”
Section: Resultsmentioning
confidence: 99%
“…By extending the linear-elastic theory of the equilibrium between interstitial solid solution atoms and host metal lattices used in several studies 6–10 , we have recently determined the degradation of elastic properties as a function of hydrogen alone, monovacancies and vacancy cluster concentrations using an analytical approach verified by DFT calculations 11 . This degradation is due more to vacancy clusters than hydrogen itself 11 .…”
Hydrogen-deformation interactions and their role in plasticity are well accepted as key features in understanding hydrogen embrittlement. In order to understand the nature of the hydrogen-induced softening process in f.c.c. metals, a substantial effort was made in this study to determine the effect of hydrogen on the tensile stress-strain behavior of nickel single crystal oriented for multiple-slips. It was clearly established that the hydrogen softening process was the result of a shielding of the elastic interactions at different scales. Hydrogen-induced softening was then formalized by a screening factor S of 0.8 ± 0.05 for 7 wppm of hydrogen, which can be incorporated into standard dislocation theory processes. The amplitude of softening suggests that the shielding process is mainly responsible for the stress softening through the formation of vacancy clusters, rather than a direct impact of hydrogen. This effect is expected to be of major importance when revisiting the impact of hydrogen on the processes causing damage to the structural alloys used in engineering.
“…7,17) With the help of the transmission electron microscopy (TEM) and the first-principles simulation, Hachet, et al have revealed that the formation of hydrogen-induced nano voids and hydrogen-vacancy culsters causes a degradation in mechanical properties of single crystal nickel alloys. 18) Unlike typical hydrogen-induced nano voids in steels and nickel alloys, numerous nano voids are formed uniformly during deformation in AlZnMgCu aluminum alloys. Neither the propagation of hydrogeninduced cracks nor the premature fracture that is attributed to the initiation and growth of nano voids has been observed in the present research.…”
Thermal spray coatings have the advantage of providing thick and functional coatings from a range of engineering materials. The associated coating processes provide good control of coating thickness, morphology, microstructure, pore size and porosity, and residual strain in the coatings through selection of suitable process parameters for any coating material of interest. This review consolidates scarce literature on thermally sprayed components which are critical and vital constituents (e.g., catalysts (anode/cathode), solid electrolyte, and transport layer, including corrosion-prone parts such as bipolar plates) of the water splitting electrolysis process for hydrogen production. The research shows that there is a gap in thermally sprayed feedstock material selection strategy as well as in addressing modelling needs that can be crucial to advancing applications exploiting their catalytic and corrosion-resistant properties to split water for hydrogen production. Due to readily scalable production enabled by thermal spray techniques, this manufacturing route bears potential to dominate the sustainable electrolyser technologies in the future. While the well-established thermal spray coating variants may have certain limitations in the manner they are currently practiced, deployment of both conventional and novel thermal spray approaches (suspension, solution, hybrid) is clearly promising for targeted development of electrolysers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
