- High-Temperature Steam Oxidation Behavior of Silicide- or Aluminide- Coated Mo and Nb Refractory Metals
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Woojin Lim, Je-Kyun Baek, JaeJoon Kim, Hyun Gil Kim, Ho Jin Ryu
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J Powder Mater. 2024;31(6):546-555. Published online December 31, 2024
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DOI: https://doi.org/10.4150/jpm.2024.00381
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 Abstract
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- Refractory materials, such as molybdenum and niobium, are potential candidates for cladding material due to their high melting temperatures and desirable mechanical properties at higher temperatures than those of zirconium alloys. However, refractory materials have low resistance to oxidation at elevated temperatures. Therefore, this study examined silicide or aluminide surface coatings as protection against rapid oxidation of refractory materials at elevated temperatures for a potential accident-tolerant fuel cladding. Silicide or aluminide layers were formed on refractory metal substrates by using the pack cementation method. The steam oxidation behavior of both coated and uncoated samples was compared by thermogravimetric analysis at 1200°C. The weight changes of the coated samples were greatly reduced than those of uncoated samples. Microstructural analyses demonstrated that the silicide and aluminide layers were oxidized to form a protective surface oxide that prevented rapid oxidation of the refractory substrate at elevated temperatures.
- Effect of Hatch Spacing on the Microstructure and Mechanical Properties of SA508 Gr.3 Steel Fabricated by Laser Powder Bed Fusion
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Yuanjiu Huang, Ho Jin Ryu, Kee-Ahn Lee
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Received December 17, 2024 Accepted December 27, 2024 Published online February 3, 2025
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DOI: https://doi.org/10.4150/jpm.2024.00479
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Abstract
- This study investigated the effect of the hatch spacing parameter on the microstructure and mechanical properties of SA508 Gr.3 steel manufactured by laser powder bed fusion (L-PBF) for a nuclear pressure vessel. Materials were prepared with varying hatch spacing (0.04 mm [H4] and 0.06 mm [H6]). The H4 exhibited finer and more uniformly distributed grains, while the H6 showed less porosity and a lower defect fraction. The yield strength of the H4 material was higher than that of the H6 material, but there was a smaller difference between the materials in tensile strength. The measured elongation was 5.65% for the H4 material and 10.41% for the H6 material, showing a significantly higher value for H6. An explanation for this is that although the H4 material had a microstructure of small and uniform grains, it contained larger and more numerous pore defects than the H6 material, facilitating stress concentration and the initiation of microcracks.
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