Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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The Variation of Microstructures and Mechanical Properties by Thermomechanical Treatment in Al-Li Based Alloys

AI-Li제 합금의 가공열처리에 따른 조직과 기계적성질의 변화

  • Kim, Ki Won (Department of Metallurgical Engineering, Chonbuk National University) ;
  • Woo, Kee Do (Department of Metallurgical Engineering, Chonbuk National University) ;
  • Lee, Kwang Ro (Department of Metallurgical Engineering, Chonbuk National University) ;
  • Lee, Min Sang (Engineering Lab., College of Eng., Chonbuk National University) ;
  • Lee, Min Ho (Engineering Lab., College of Eng., Chonbuk National University) ;
  • Hwang, Ho Eul (Institute of Technology, Sam Sun Co., Ltd.)
  • 김기원 (전북대학교 공과대학 금속공학과) ;
  • 우기도 (전북대학교 공과대학 금속공학과) ;
  • 이광로 (전북대학교 공과대학 금속공학과) ;
  • 이민상 (전북대학교 공과대학 공동시험소) ;
  • 이민호 (전북대학교 공과대학 공동시험소) ;
  • 황호을 (삼선공업(주) 기술연구소)
  • Published : 1991.09.30
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Abstract

The present work was aimed to examine the variation of precipitations and mechanical properties by thermomechanical treatments (TMT) in Al-2.19 wt%Li and Al-2.0 wt%Li-0.11 wt%Zr alloys. This study was performed by TEM, SEM observation, DSC, electrical resistance measurement, hardness and tensile strength measurement. First peak of resistivity aged at $90^{\circ}C$ was caused by precipitation of ${\delta}^{\prime}$-precursor phase, and second peak was caused by precipitation of ${\delta}^{\prime}$ phase. According to this result, the precipitation process of Al-2.19 wt%Li alloy was as follow : $SSSS{\rightarrow}{\delta}^{\prime}$-precursor phase ${\rightarrow}{\delta}^{\prime}$ (Coherent ${\rightarrow}$ Semi-coherent) ${\rightarrow}{\delta}$. In a Al-2.0 wt%Li-0.11 wt%Zr ternary alloy, the first peak of resistivity was appeared at initial aging heat-treatment. It is result from exsistant of ${\delta}^{\prime}$-precursor phase. The effect acceleration in a binary alloy was not appeared and the over-aging ternary alloy was accelerated with increase of the reduction rate. It is caused by combination effect of ${\delta}^{\prime}$ and composite phase.

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