Abstract
The microstructure, the segregation and the evolution of γ/γ' eutectic during the solidification of Ni-base superalloy DD6 prepared by dual heating zone melting and liquid-metal cooling (LMC) direction solidification technique were investigated over a range of cooling rates. The microsegregation behavior during solidification was also quantitatively examined by EPMA to clarify the influence of elemental segregation on the evolution of γ/γ' eutectic. The effect of dendrite arm spacing was also taken into consideration. The results demonstrate that the γ/γ' eutectic fraction first increases and then decreases with the increasing of cooling rate. The back-diffusion in solid phase would reduce the microsegregation during dendrite growth. Back-diffusion occurs during the solidification of Ni-based single crystal superalloy DD6, but its influence on decreasing of the volume fraction of γ/γ' eutectic would be negligible depending on the diffusivity of each solute element when the cooling rate is up to a certain limit. As the cooling rate increases, the dilution effect of microsegregation owing to dendrite arm spacing decrease plays a leading role during solidification.
| Original language | English |
|---|---|
| Pages (from-to) | 2547-2552 |
| Number of pages | 6 |
| Journal | Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering |
| Volume | 42 |
| Issue number | 12 |
| State | Published - 2013 |
Keywords
- Dendrite arm spacing
- Eutectic
- Ni-based single crystal superalloy
- Segregation
- Solute partition coefficient