Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Aging Behaviors of a Rapidly Solidified AI-Li-Cu Alloy

급냉응고된 Al-Li-Cu 합금의 시효거동

  • Hong, Y.J. (Defence Quality Assurance Agent) ;
  • Kim, S.H. (Department of Metallurgical Engineering, Pusan National University) ;
  • Kang, M.C. (Department of Metallurgical Engineering, Pusan National University) ;
  • Kim, I.B. (Department of Metallurgical Engineering, Pusan National University)
  • 홍영준 (국방 품질 검사소) ;
  • 김순호 (부산대학교 공과대학 금속공학과) ;
  • 강민철 (부산대학교 공과대학 금속공학과) ;
  • 김인배 (부산대학교 공과대학 금속공학과)
  • Published : 1993.09.30
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Abstract

Effects of aging treatment on the microstructural evolution of a rapidly solidified Al-Li-Cu alloy were investigated by differential scanning calorimetry (DSC) and transmission electron microscopy(TEM). It was found that the precipitation sequence was: supersaturated solid solution ${\alpha}^{\prime}$ ${\rightarrow}$ metastable ${\delta}^{\prime}$ + stable precipitate $T_1$ ${\rightarrow}$ stable precipitates ${\delta}+T_1$. Two exothermic and two endothermic peaks are detected by DSC analysis. The two exothermic and endothermic peaks corresponded to ${\delta}^{\prime}$ and ${\delta}+T_1$ precipitation and dissolution reactions respectively. The enthalpy of ${\delta}^{\prime}$ precipitation decreased with increasing of aging temperature and time until the finishing point of precipitation. The activation energy for precipitation of ${\delta}^{\prime}$ was measured as 80KJ/mol and the energy for dissolution was 93KJ/mol. These values arc higher than those of AI-Li binary alloy. Peak hardness value (Hv 170) was obtamed at $210^{\circ}C$ for 1hr aging treatment which coincided with finishing point of ${\delta}^{\prime}$ precipitation.

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