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MM: Fachverband Metall- und Materialphysik

MM 4: Materials for the Storage and Conversion of Energy

MM 4.6: Vortrag

Montag, 17. März 2025, 11:30–11:45, H22

Hydrogen: a catalyst for abnormal grain growth in inert-gas condensed nanocrystalline Pd-Au? — •Fabian Andorfer¹, Jules M. Dake¹, Markus Ziehmer¹, Johannes Wild², Torben Boll², Dorothée Vinga Szabó², Stefan Wagner², Astrid Pundt², and Carl E. Krill III¹ — ¹Institute of Functional Nanosystems, Ulm University — ²Institute of Applied Materials - Materials Science and Engineering (IAM-WK), Karlsruhe Institute of Technology

Heat treatment causes some polycrystalline materials to manifest abnormal grain growth (AGG), during which a few grains acquire a significant growth advantage compared to the remaining matrix grains, resulting in a bimodal distribution of grain sizes. Inert-gas condensed nanocrystalline Pd-Au alloys undergo an extreme form of AGG. This system is known to absorb hydrogen. When Pd-Au alloys are exposed to hydrogen below a certain gas pressure, hydrogen atoms primarily occupy grain boundaries and interstitial sites. This segregation is expected to lower the excess energy of the grain boundaries, which should have a noticeable effect on subsequent grain growth. To test this, Pd-Au samples were heat treated in argon and hydrogen atmospheres, respectively. The average size of the abnormally grown grains was determined, and the grain shape was characterized by calculating the circularity. Hydrogen appeared to increase the rate of abnormal grain nucleation” without affecting the resulting grain shape.

Keywords: Hydrogen; Abnormal Grain Growth; Palladium; Gold; Boundary Energy