Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Microstructural Evolution of Cu-15 wt%Ag Composites Processed by Equal Channel Angular Pressing

등통로각압축공정을 이용하여 제조된 Cu-15 wt%Ag 복합재의 미세구조

  • Lee, In Ho (Department of Nano Materials Engineering, Chungnam National University) ;
  • Hong, Sun Ig (Department of Nano Materials Engineering, Chungnam National University) ;
  • Lee, Kap Ho (Department of Nano Materials Engineering, Chungnam National University)
  • 이인호 (충남대학교 나노소재공학과) ;
  • 홍순익 (충남대학교 나노소재공학과) ;
  • 이갑호 (충남대학교 나노소재공학과)
  • Received : 2012.03.07
  • Published : 2012.12.25
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Abstract

The microstructure of Cu-15 wt%Ag composites fabricated by equal channel angular pressing (ECAP) with intermediate heat treatment at $320^{\circ}C$ was investigated by transmission electron microscopy (TEM) observations. Ag precipitates with a thickness of 20-40 nm were observed in the eutectic region of the Cu-15 wt%Ag composite solution treated at $700^{\circ}C$ before ECAP. The Cu matrix and Ag precipitates had a cube on cube orientation relationship. ECAPed composites exhibited ultrafine-grained microstructures with the shape and distribution dependent on the processing routes. For route A in which the sample was pressed without rotation between each pass, the Cu and Ag grains were elongated along the shear direction and many micro-twins were observed in elongated Cu grains as well as in Ag filaments. The steps were observed on coherent twin boundaries in Cu grains. For route Bc in which the sample was rotated by 90 degrees after each pass, a subgrain structure with misorientation of 2-4 degree by fragmentation of the large Cu grains were observed. For route C in which the sample was rotated by 180 degrees after each pass, the microstructure was similar to that of the route A sample. However, the thickness of the elongated grains along the shear direction was wider than that of the route A sample and the twin density was lower than the route A sample. It was found that more microtwins were formed in ECAPed Cu-15 wt%Ag than in the drawn sample. Grain boundaries were observed in relatively thick and long Ag filaments in Cu-15 wt%Ag ECAPed by route C, indicating the multi-crystalline nature of Ag filaments.

Keywords

Acknowledgement

Supported by : 지식경제부

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