• Title/Summary/Keyword: 초소성 합금

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Superplastic Properties of Al-Mg-Cu-Mn Alloys (Al-Mg-Cu-Mn 합금의 초소성 특성)

  • Park, Jong-U;Kim, Hui-Su;Mun, In-Gi;Ha, Gi-Yun;Lee, Deok-Yeol
    • Korean Journal of Materials Research
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    • v.5 no.1
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    • pp.132-139
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    • 1995
  • Tnermomechanical treatment consisting of homogenizing, hot and warm rolling were introduced to Al-MgCu-Mn alloys for obtaining superplasticity. The factors affecting the superplasticity of the alloys were investigated by optical and transmission electron microscopy. Large particles which had not been decomposed during homogenizing treatments remained stable in the hot and warm rolling processes. These particles were a source of cavitation and poor elongation in superplastic deformation. On the other hand, fine precipitates were produced during thermomechanical processing, and resulted in improvement of superplasticity by stabilizing microstructure. Two-step homogenizing and air cooling process was more effective than onestep homogenizing and furance cooling process in removing microsegregations and producing fine particles.

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Superplastic Microextrusion for Microgears (초소형 기어 제조를 위한 초소성 재료의 미세압출)

  • Kim, Jae-Yeon;Joo, Se-Min;Kim, Ho-Kyung
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.4
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    • pp.1-7
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    • 2008
  • Fine grained superplastic Zn-22%Al alloy was extruded using a laser machined micro-die to produce a micro-gear shaft. Extrusion process was conducted under a constant pressure at constant temperatures ranging from 503 to 563K. Laser machining was capable to machine a micro-die with close tolerances and adequate surface quality. The extrusion rate increased with extrusion load under constant extrusion temperature. The rate reached a steady state and became constant after a certain period. There was a small instantaneous stroke on application of the load and then a very brief primary stage which preceded steady-state flow. The micro-extrusion process was proven to produce a micro-gear shaft successfully using a fine grained superplastic Zn-22%Al alloy.