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Effect of CaO Addition on Age Hardening Behavior of AZ91 Alloy

AZ91 합금의 시효경화 거동에 미치는 CaO 첨가의 영향

  • Jun, Joong-Hwan (Advanced Fusion Process R&D Group, Korea Institute of Industrial Technology)
  • 전중환 (한국생산기술연구원 융합신공정연구그룹)
  • Received : 2011.06.07
  • Accepted : 2011.06.24
  • Published : 2011.07.30

Abstract

Effect of CaO addition on age hardening response has been studied by using optical microscopy, scanning electron microscopy and differential thermal analysis in AZ91 and CaO-containing ECO-AZ91 alloys. After solution treatment, the ${\beta}$($Mg_{17}Al_{12}$) phase formed during solidification mostly disappeared in the microstructure in the AZ91 alloy, whereas numerous ${\beta}$ precipitates containing Ca were still observed in the ECO-AZ91 alloy due to its enhanced thermal stability. The ECO-AZ91 alloy showed the delayed peak aging time and higher peak hardness compared with those of the AZ91 alloy. The activation energies for ${\beta}$ precipitation calculated by means of Kissinger method increased from 71.4 to 85.6 kJ/mole by the addition of CaO, which implies that CaO plays a role in reducing ${\beta}$ precipitation rate in the AZ91 alloy.

Keywords

References

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