- Effect of Process Parameters on Microstructure and Magnetic Properties of Sm-Co Alloy Powder Prepared by High Energy Ball Milling
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Bo-Sik Kim, Si-Young Chang
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J Korean Powder Metall Inst. 2010;17(2):130-135.
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DOI: https://doi.org/10.4150/KPMI.2010.17.2.130
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 Abstract
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- Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to 110;µm. After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately 5;µm, which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately 7;µm at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.
- The Aging Characteristics of Mg-6 wt.% Al-1 wt.% Zn Alloy Prepared by Gas Atomization
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Du-Hyung Lee, Bo-Sik Kim, Si-Young Chang
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J Korean Powder Metall Inst. 2009;16(4):275-279.
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DOI: https://doi.org/10.4150/KPMI.2009.16.4.275
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Abstract
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- The aging characteristics of gas atomized Mg-6 wt.% Al-1 wt.% Zn alloy were investigated and compared to those of cast Mg-6 wt.% Al alloy. The gas atomized Mg-6 wt.% Al-1wt.% Zn alloy powders had spherical morphology between 1 and 100 mu m in diameter. After compaction under the pressure of 700 MPa at 320°C for 10 min, the Mg-6 wt.% Al-1 wt.% Zn alloy showed a grain size of approximately 40 mu m which is smaller than that of the cast Mg-6 wt.% Al alloy, and a relative compact density of approximately 93%. After ageing, the Mg-6 wt.% Al-1 wt.% Zn alloy showed much faster peak hardness than cast Mg-6 wt.% Al alloy. The Mg-6 wt.% Al-1 wt.% Zn alloy showed the new fine precipitations with ageing time, while the cast Mg-6 wt.% Al alloy was almost similar morphology.
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