A study on the MC Carbide Morphologies Directionally Solidified Superalloys

일방향응고 초내열합금에서 MC 탄화물 형상에 관한 연구

  • 김승언 (한국기계연구원 내열재료실) ;
  • 조창용 (한국기계연구원 내열재료실) ;
  • 김학민 (한국기계연구원 내열재료실)
  • Published : 1990.12.20

Abstract

The morphologies of MC carbides (M stands for metal) and creep-rupture properties in directionally solidified Rene 80 having standard and Hf-modified chemistries were studied. It was found that Hf depressed the melting point, $\gamma$- $\gamma$’ eutectic temperature and $\gamma$’ solvus of nickel-base superalloy Rene 80, but did not depress MC carbide forming temperature. The morphologies of MC carbides depended upon solidification sequence, which led to blocky type in the early stage and script type in the late stage of solidification. Creep failure occurs through the crack initiation at the transverse components of longitudinal grain boundaries or interdendritic carbides in directionally solidified superalloys. It could be concluded MC carbide morphologies played an important role in creep properties of DS superalloys, that is, Hf additions increased the creep ductilities and lives of Rene 80.

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