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<p>Any metal alloy powder synthesized by solid-state hydrogen reduction of metal oxides should be chemically homogeneous for direct conversion into a versatile product. In this study, a 50-wt.% Fe<sub>2</sub>O<sub>3</sub>-NiO powder mixture was reduced using hydrogen for 45&#xa0;min at 700°C and homogenized in argon at 1100°C. The absence of oxygen in the as-reduced and homogenized powders was confirmed via exhaust gas analysis and X-ray diffractometry. Three homogenization times, 5, 10, and 15&#xa0;h, were tested in experimental trials based on simulation results. Energy-dispersive X-ray spectroscopy in a scanning electron microscope revealed few iron-rich sites in the sample homogenized for 5&#xa0;h, a predominance of iron in the sample homogenized for 10&#xa0;h, and a homogeneous composition after 15&#xa0;h of homogenization. The 15-h-homogenized powder exhibited relatively extensive neck growth and minimal porosity, indicating suitability for direct use. Iron- and nickel-free impurities from the Fe<sub>2</sub>O<sub>3</sub> feedstock were observed on and within powder particle boundaries. They were non-detrimental to the reduction and homogenization processes. These results demonstrate that solid-state reduction and homogenization at 1100°C for 15&#xa0;h yield a microscopically homogeneous alloy powder, sinterable into a solid product. The findings are generalizable to other alloy systems and higher-order oxide mixtures.</p>

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Diffusion Model-Guided Improvement of Chemical Homogeneity in Iron–Nickel Alloy Powder Synthesized by Solid-State Hydrogen Reduction

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月14日

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  • Arun Kamalasekaran,
  • Pelle Mellin,
  • Christopher Hulme

摘要

Any metal alloy powder synthesized by solid-state hydrogen reduction of metal oxides should be chemically homogeneous for direct conversion into a versatile product. In this study, a 50-wt.% Fe2O3-NiO powder mixture was reduced using hydrogen for 45 min at 700°C and homogenized in argon at 1100°C. The absence of oxygen in the as-reduced and homogenized powders was confirmed via exhaust gas analysis and X-ray diffractometry. Three homogenization times, 5, 10, and 15 h, were tested in experimental trials based on simulation results. Energy-dispersive X-ray spectroscopy in a scanning electron microscope revealed few iron-rich sites in the sample homogenized for 5 h, a predominance of iron in the sample homogenized for 10 h, and a homogeneous composition after 15 h of homogenization. The 15-h-homogenized powder exhibited relatively extensive neck growth and minimal porosity, indicating suitability for direct use. Iron- and nickel-free impurities from the Fe2O3 feedstock were observed on and within powder particle boundaries. They were non-detrimental to the reduction and homogenization processes. These results demonstrate that solid-state reduction and homogenization at 1100°C for 15 h yield a microscopically homogeneous alloy powder, sinterable into a solid product. The findings are generalizable to other alloy systems and higher-order oxide mixtures.