Hydrogen Embrittlement in Advanced Alloys: Mechanisms and Mitigation

Hydrogen embrittlement (HE) is a phenomenon where materials lose ductility and strength due to the absorption of hydrogen. This can lead to sudden, catastrophic failure under stress, even at loads below the material’s yield strength. HE primarily affects high-strength steels, titanium alloys, aluminum alloys, and some nickel-based alloys. Materials with high tensile strength and hardness are particularly vulnerable. The severity depends on factors such as hydrogen concentration, stress state, temperature, and material microstructure. HE is critical in industries like aerospace, automotive, and energy, where hydrogen exposure is common, making it a significant challenge for material reliability and structural integrity.

HE remains poorly understood due to the complexity of hydrogen-material interactions, including its diffusion, trapping, and effect on microstructural features like dislocations, grain boundaries, and phase interfaces. The precise mechanisms—whether hydrogen-enhanced decohesion, localized plasticity, or hydride formation—vary across materials and conditions, complicating predictive models. Our past research on embrittlement of metals has shown that an oft-ignored surface thermodynamic parameter – surface stress—plays a critical role in the inducing fracture [1,2,3]. We have demonstrated that by control of surface stress through organic monolayers, we can not only induce embrittlement in an otherwise ductile material but also suppress fracture in a brittle one. These results open new avenues to study HE and means to suppress it.

We will investigate hydrogen embrittlement (HE) through an integrated experimental and modeling approach. Experimentally, we will develop advanced metrology techniques using Single Edge Notched Beam (SENB) samples. These samples will be systematically exposed to hydrogen via environments such as aqueous media or high-pressure chambers. Post-exposure, we will quantify hydrogen concentration using techniques like thermal desorption spectroscopy and correlate it with changes in fracture toughness. We will also measure changes in surface quantities such as surface energy, surface stress and obtain correlations with the any phenomenological change in the fracture behavior. We will study the role of protective coatings and hydrogen embrittlement inhibitors [4] in altering the fracture behavior of the metal. Various advanced surface analytical techniques and electrochemical methods [5] will be used to characterize the metal surface, hydrogen permeation and hydrogen embrittlement behavior. The effects of surface coating and inhibitor layers on surface energy, and on HE processes and mechanisms will be elucidated. ;

On the modeling front, we will create a multiscale framework. Atomistic simulations will explore interactions between hydrogen and microstructural features, including dislocations and grain boundaries. Insights from these simulations will inform a phase-field model capable of predicting crack propagation paths as a function of hydrogen concentration and fracture toughness.;

We anticipate that this research will provide actionable insights for material design in hydrogen storage, transport systems, and structural applications in clean energy technologies. Understanding HE could revolutionize material design, enabling the development of hydrogen-resistant alloys, improved coatings, and enhanced processing methods. This would ensure the safe and reliable adoption of hydrogen-based technologies in energy, transportation, and infrastructure, thereby advancing clean energy initiatives and reducing catastrophic material failures in critical applications. Publications in esteemed journals, patents, external funding and industrial collaborations are all likely outcomes of this project. ;

;References

1. Sugihara, T., Udupa, A., Viswanathan, K., Davis, J.M. and Chandrasekar, S., 2020. Organic monolayers disrupt plastic flow in metals. Science advances, 6(51), p.eabc8900.;

2. Udupa, A., Sugihara, T., Viswanathan, K., Latanision, R.M. and Chandrasekar, S., 2021. Surface-stress induced embrittlement of metals. Nano Letters, 21(22), pp.9502-9508.;

3. Udupa, A., Mohanty, D.P., Sugihara, T., Mann, J.B., Latanision, R.M. and Chandrasekar, S., 2024. Surface stress can initiate environment-assisted fracture in metals. Physical Review E, 109(2), p.L023002.;

4. Z. Wang, B. Varela, A. Somers, M.Y. Tan, Probing the efficiency and mechanism of hydrogen permeation inhibition in pipeline steel by organic inhibitors, International Journal of Hydrogen Energy 85 (2024) 135–146. https://doi.org/10.1016/j.ijhydene.2024.08.341.;

5. M.Y. Tan, R.W. Revie, Heterogeneous Electrode Processes and Localized Corrosion, Wiley, 2012. https://books.google.com.au/books?id=BFbwjYRYxV0C.;