Making Strong Alloys Ductile and Hydrogen-Tolerant through Engineering Gradient Nanostructures

R&D Focus Areas:
Hydrogen embrittlement, Advanced manufacturing

Lead Organisation:
The University of Sydney

Partners:
The University of Queensland

Status:
Active

Start date:
January 2023

Completion date:
December 2026

Key contacts:
Xianghai An (xianghai.an@sydney.edu.au)

Funding:
Australian Research Council (Discovery Project)
Sydney Nano Institute Kickstarter funding

Project total cost:
Approximately AUD$800,000 – combined cash and in-kind contribution

 Project summary description:
High-performance alloys are the backbone of decarbonising innovations in manufacturing, infrastructure, energy, and transportation. There is an accelerated demand for high-strength materials to produce lighter, more-reliable structural components. Stronger alloys will substantially improve mechanical and energy efficiencies, which can benefit our economy and environment directly. However, high-strength materials typically have low ductility and are more vulnerable to fracture. Furthermore, they are also particularly susceptible to hydrogen embrittlement (HE) in many service environments for renewable energy applications such as hydrogen transportation and the bearings of wind turbines.

Hydrogen-induced embrittlement can lead to unpredictable and catastrophic failures at relatively low applied stresses. These critical shortcomings cause serious safety concerns but cannot be readily addressed by traditional materials development approaches that generally render materials property trade-offs between strength and ductility/HE resistance. Therefore, a novel design strategy is needed to produce strong, ductile, and hydrogen-compatible alloys to meet the increasingly stringent property demands for engineering applications, especially for the evolving hydrogen-based industries.

Gradient structures are an emerging material-design paradigm inspired by nature that has great potential to overcome these alloy design trade-offs. This project aims to develop an innovative design strategy of gradient segregation engineering (GSE) to produce high-performance alloys by synergistically introducing a chemical gradient via grain boundary (GB) segregation and a physical gradient by nanostructure control.

The novel GSE will entail a synergy of multiscale strengthening mechanisms that offer an exceptional strength-ductility combination and simultaneously enable the hierarchical HE-resisting mechanisms to notably enhance the hydrogen tolerance.

The specific aims of this project are:

• Tailor gradient nanostructures and solute segregations to achieve an optimal combination of high strength, high ductility, and high HE resistance in Fe-Mn steels to demonstrate this novel material-design strategy.
• Elucidate how the GSE can subtly activate and coordinate multiple strengthening and toughening mechanisms over different length scales that enable an exceptional combination of strength, ductility, and HE resistance.
• Develop a new correlative characterisation protocol to quantify how the solute segregation at GBs regulates the local plasticity using atom probe tomography (APT) after in-situ deformation testing in a transmission electron microscope (TEM), establishing the robust structure-chemistry-properties relationships for GSE materials.
• Quantitatively determine the HE resistance of bulk GSE materials via macroscopic mechanical testing and the measurement of hydrogen retention and permeability.
• Quantitatively verify the susceptibility of local microstructural features to hydrogen-induced damage via the newly developed cryo-APT and micromechanical testing to depict the precise HE-resisting mechanism.

Higher degree studies supported:
Two PhD students and two Master of Philosophy students at The University of Sydney are supported by this project.
One PhD student at The University of Queensland is supported by this project.

 

September 2023