Reaction kinetics study of hydrogen reduction of high energy milled CoCrFeNi high-entropy alloy (HEA)
In this study, an equimolar CoCrFeNi high-entropy alloy (HEA) was fabricated via ball milling and hydrogen reduction to assess the feasibility of hydrogen reduction of chromium oxide in chromium based HEAs. High-energy milling of metal oxide powders (Co3O4, Cr2O3, NiO and α-Fe2O3) at 2400 rpm produc...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-03-01
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| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425004430 |
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| Summary: | In this study, an equimolar CoCrFeNi high-entropy alloy (HEA) was fabricated via ball milling and hydrogen reduction to assess the feasibility of hydrogen reduction of chromium oxide in chromium based HEAs. High-energy milling of metal oxide powders (Co3O4, Cr2O3, NiO and α-Fe2O3) at 2400 rpm produced a homogeneous solid solution, with particle sizes reduced from 60.74 nm at 5 h and 39.84 nm at 30 h milling time. Thermogravimetric analysis (TGA) at varying heating rates was employed, and the Kissinger–Akahira–Sunose (KAS) method was used to compare the reaction kinetics between 5 h and 30 h milled HEA. The 5 h milled HEA reached a conversion fraction of reaction up to 0.71 at 996 °C, while the 30 h milled HEA achieved a conversion of approximately 0.75 at 881 °C. TGA analysis of 30 h milled HEA revealed a 17.3% degree of Cr2O3 reduction without holding time and 52.7 % degree of Cr2O3 reduction after 3 h hold at 1000 °C. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) confirmed nano-sizing, homogeneity, and phase transformation with increased milling time. The results demonstrate that extended milling enhances microstructural development and hydrogen reduction, potentially making this process a viable alternative to gas atomization for creating CoCrFeNi HEA nanopowder agglomerates for specialized applications. |
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| ISSN: | 2238-7854 |