- The Role of H2O as PCA and the Precipitation Behavior in Mechanically Alloyed Ni-20Cr-20Fe-5Nb Alloy
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Il-Ho Kim, S.I. Kwun, Won-Sik Lee, S.W. Chae, S.K. Hwang, M.H. Kim
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J Korean Powder Metall Inst. 2006;13(3):178-186.
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DOI: https://doi.org/10.4150/KPMI.2006.13.3.178
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 Abstract
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- The effect of use of H_2O as PCA(process control agent) to prevent the carbon contamination during mechanical alloying process and the precipitation behavior in Ni-20Cr-20Fe-5Nb bulk alloy after aging were investigated. NbC and Cr_2O_3 were formed during mechanical alloying and consolidation processes in the Ni-20Cr-20Fe-5Nb alloy in which methanol(CH_3OH) was added as PCA. Formation of NbC in this alloy decreased the amount of Nb dissolved in the Ni matrix. The use of H_2O as PCA in Ni-20Cr-20Fe-5Nb alloy prevented the formation of NbC and increased the hardness. The increase of hardness in this alloy was attributed to the increased amount of Nb dissolved in the Ni matrix. After aging treatment for 20 hours at 600°C;and;720°C of Ni-20Cr-20Fe-5Nb bulk alloy in which H_2O added as PCA, gamma"(Ni_3Nb,;tetragonal);and;delta;(Ni_3Nb,;orthorhombic) precipitates were formed, respectively. The precipitation temperatures of gamma" and delta in this bulk alloy were lower than those in commercial IN 718 alloy. It seemed that the lower precipitation temperatures for gamma" and delta in this bulk alloy than in commercial IN 718 alloy were due to severe plastic deformation during mechanical alloying.
- Fabrication of Graphite-Ni Composite Powders and Effect of Thermal Spray Coating Parameters on Mechanical and Microstructural Properties
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Joon-Chul Kwon, Mun-Kwan Cho, Il-Ho Kim, Tae-Whan Hong, Soon-Yong Kweon, Young-Geun Lee, Soon-Wook Park, Soon-Chul Ur
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J Korean Powder Metall Inst. 2005;12(2):136-145.
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DOI: https://doi.org/10.4150/KPMI.2005.12.2.136
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- Graphite-Ni composite powders were synthesized by mechanical alloying(MA) and spray drying(SD). Fabricated powders as well as commercial graphite-Ni powders were thermally sprayed on mild steel substrates using high velocity oxygen fuel (HVOF) thermal spray process and flame thermal spray process. The effects of several process parameters on related properties in thermally sprayed coatings have been investigated and correlated with microstructures in this study. The results indicated that the desired properties can be obtained when commercial powders were applied using HVOF process, while coating properties in case of MA powder application were inferior to those in HVOF process in so far. However, it is suggested that property enhancement can be obtained if the fraction of hexagonal graphite phase can be increased in mechanically alloyed powders.
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Citations
Citations to this article as recorded by  - The Effect of Graphite Content on the Wear Behavior of Ni/WC/G Composite Coating
Gui Rong Yang, Chao Peng Huang, Wen Ming Song, Ying Ma, Yuan Hao
Advanced Materials Research.2015; 1120-1121: 702. CrossRef
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