• Title/Summary/Keyword: Metallic powders

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Effects of Phase Fraction and Metallic Glass-Diamond Size Ratio on the Densification of Metallic Glass/Diamond Composite (비정질/다이아몬드 복합재료에서 상분율과 비정질-다이아몬드 입자 크기 비가 성형특성에 미치는 영향)

  • Shin, Su-Min;Kim, Taek-Soo;Kang, Seung-Koo;Kim, Jeong-Gon
    • Journal of Powder Materials
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    • v.16 no.3
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    • pp.173-179
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    • 2009
  • In the present study, Zr-base metallic glass(MG)/diamond composites are fabricated using a combination of gas-atomization and spark plasma sintering (SPS). The densification behaviors of mixtures of soft MG and hard diamond powders during consolidation process are investigated. The influence of mixture characteristics on the densification is discussed and several mechanism explaining the influence of diamond particles on consolidation behaviour are proposed. The experimental results show that consolidation is enhanced with increasing diamond/Metallic Glass(MG) size ratio, while the diamond fraction is fixed.

Bulk Amorphous and/or Nanocrystalline Finemet Alloy Prepared by Super-high-pressure Consolidation

  • Lu, Wei;Yanb, Biao
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.788-789
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    • 2006
  • Microstructure and soft magnetic properties of bulk amorphous and/or nanocrystalline $Fe_{73.5}Cu_1Nb_3Si_{13.5}B_9$ alloys prepared by consolidation at 5.5GPa were investigated. The relative density of the bulk sample 1 (from amorphous powders) was 98.5% and the grain sizes were about 10.6nm. While the relative density and grain sizes of bulk sample 2 (from nanocrystalline powders) are 98% and 20.1nm, respectively. Particularly, the bulk samples exhibited a good combined magnetic property: for Sample1, $M_s=125emu/g$ and $H_c=1.5Oe;$ for Sample2, $M_s=129emu/g$ and $H_c=3.3Oe$. The success of synthesizing the nanocrystalline Fe-based bulk alloys will be encouraging for the future development of bulk nanocrystalline soft magnetic alloys.

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Effect of Powder Morphology on the Deposition Quality for Direct Laser Melting (Direct Laser Melting 공정시 분말 형태가 적층 품질에 미치는 영향)

  • Lee, S.H.;Kil, T.D.;Han, S.W.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.25 no.3
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    • pp.195-202
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    • 2016
  • Direct laser melting(DLM) is an additive manufacturing process that can produce parts by solidification of molten metallic powder layer by layer. The properties of the fabricated parts strongly depend on characteristics of the metallic powder. Atomized powders having spherical morphology have commonly been used for DLM. Mechanical ball-milling is a powder processing technique that can provide non-spherical solid powders without melting. The aim of the current study was to investigate the effect of powder morphologies on the deposition quality in DLM. To characterize the morphological effect, the performances of spherical and non-spherical powders were compared using both single- and multi-track DLM experiments. DLM experiments were performed with various laser process parameters such as laser power and scan rate, and the deposition quality was evaluated. The surface roughness, cross-section bead shape and process defects such as balling or non-filled area were compared and discussed in this study.

Crystallization behavior of Cu-base bulk metallic glass in supercooled liquid region during compression and tension (과냉각 액상구간에서 압축.인장시 Cu기 비정질 합금의 결정화 거동)

  • Park, E.S.;Kim, S.H.;Huh, M.Y.;Kim, H.W.;Bae, J.C.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.215-217
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    • 2008
  • Crystallization behavior of the bulk metallic glass (BMG) during compression and tension was studied in the supercooled liquid region (SLR). Rod samples of the BMG alloy were produced by consolidating gas atomized powders of $Cu_{54}Zr_{22}Ti_{18}Ni_6$ using spark plasma sintering. The crystallization behavior in these samples was examined by tackling changes in thermal property during heating the samples in DSC. The present BMG alloy was firstly decomposed and then crystallized during annealing in the SLR. The phase decomposition from the original amorphous phase was retarded by the compressive stress, while it was accelerated by the tensile stress.

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