Acta Student Award 2025 recognizes paper on strengthening effects in advanced alloys
Acta Journals recognize Chengguang Wu’s research
At a glance:
- Award: Acta Student Award 2025 by Acta Materialia.
- Awardee: Dr Chengguang Wu, postdoctoral researcher at the Max Planck Institute for Sustainable Materials.
- Research focus: Understanding how hydrogen behaves in refractory complex concentrated alloys.
- Outcome: The findings establish hydrogen as a potential alloy-design tool rather than solely a source of material degradation.
The Acta Journals have awarded Dr Chengguang Wu, postdoctoral researcher at the Max Planck Institute for Sustainable Materials, an Acta Student Award 2025 for his publication about the strengthening effects of hydrogen in refractory complex concentrated alloys. The award is endowed with 2,000 $.
Hydrogen is often regarded as a challenge for metallic materials because it can cause embrittlement and reduce component lifetime. However, Wu demonstrates that hydrogen can also actively drive nanoscale chemical redistribution to tailor microstructures of complex alloys and improve their mechanical performance.
The research investigates how hydrogen interacts with a refractory complex concentrated alloy composed of titanium, niobium, zirconium, hafnium and tantalum (TiNbZrHfTa), and its potential strengthening effects. The findings provide new insights into hydrogen-metal interactions and open up new opportunities for designing materials for future hydrogen technologies.
Turning a challenge into an opportunity
As hydrogen becomes increasingly important for clean energy production, storage and transport, understanding how it interacts with structural materials, especially refractory alloys, is essential. Hydrogen atoms are exceptionally small and can easily penetrate metallic lattices. This penetration has traditionally been viewed as detrimental, as hydrogen can weaken metals and lead to failure. The new study offers a new perspective by showing that hydrogen can also trigger beneficial microstructural changes.
“This award is a tremendous validation of our research and truly the best conclusion to my PhD work”, says Wu. Together with his colleagues, he exposed an equiatomic TiNbZrHfTa alloy to hydrogen gas at 500°C and observed an unexpected phenomenon: hydrogen-assisted spinodal decomposition. This process causes the initially homogeneous alloy to decompose into nanoscale domains characterized with distinct chemical compositions.
Visualising nanoscale transformations
Using advanced three-dimensional atom probe tomography, the researchers tracked how the alloy evolved during hydrogen exposure. They discovered periodic compositional modulations at the nanoscale, with zirconium and titanium becoming concentrated in one phase, while niobium and tantalum accumulated in another. The resulting needle-shaped nanostructures formed along specific crystallographic directions that minimise elastic strain energy within the material.
To understand the underlying mechanism, the researchers developed a statistical thermodynamic model that explicitly incorporates hydrogen. The model revealed that hydrogen destabilises the original single-phase alloy by expanding the spinodal region, making phase separation thermodynamically favourable.
Improved hardness and wear resistance
The spinodal decomposition significantly increased the alloy's hardness and resistance to wear.
These findings demonstrate that hydrogen absorbed from the environment can be used as a tool to modify local chemical and structural patterns within an alloy. Rather than acting solely as a harmful element, hydrogen can become an interstitial alloying element that helps engineer desirable properties.
Recognising outstanding early-career research
The study was recognised with an Acta Student Award, which honours exceptional contributions by student researchers who published in one of the Acta journals. Each year, up to 16 awards are presented to students, highlighting excellence in materials science and engineering at an early stage of a research career. The awardees are encouraged to attend The Minerals, Metals and Materials Society (TMS) Conference of the following year and are supported by a reimbursement of their travel expenses.
