Acta Metallurgica Sinica (English Letters) ›› 2023, Vol. 36 ›› Issue (7): 1173-1178.DOI: 10.1007/s40195-022-01469-5

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Characterization of Compositionally Complex Hydrides in a Metastable Refractory High-Entropy Alloy

Jikui Liu1, Junhua Hou1, Fengchao An1, Bingnan Qian1, Christian H. Liebscher2(), Wenjun Lu1()   

  1. 1Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
    2Max-Planck-Institut Für Eisenforschung, Max-Planck-Straße 1, 40237, Düsseldorf, Germany
  • Received:2022-06-16 Revised:2022-07-22 Accepted:2022-07-31 Online:2023-07-10 Published:2023-07-04
  • Contact: Christian H. Liebscher, Wenjun Lu

Abstract:

Here, we study the hydride formation in a metastable Ti-33Zr-22Hf-11Ta (at.%) refractory high entropy alloy (RHEA). Deviating to non-equiatomic compositions of RHEAs promotes the formation of transformation-induced plasticity where the body-centered cubic phase transforms to hexagonal close-packed (HCP) phase. It is found that the phase transformation capability assists the hydride formation due to the low solubility of hydrogen within the HCP phase. In this study, hydrogen is charged via electrochemical polishing and the corresponding phase transformation is activated in the metastable RHEAs. The newly formed HCP phase interacts with hydrogen to form a face-centered cubic hydride verified by electron energy loss spectroscopy. This work provides a primary exploration of the formation of compositionally complex metal hydrides in the metastable RHEAs, which are potential candidates for future hydrogen storage material design.

Key words: Refractory high entropy alloy, Compositionally complex hydrides, Electrochemical polishing, Phase transformation, Scanning transmission electron microscopy (STEM)/electron energy loss spectroscopy (EELS)