| Title |
Research Paper / Solidification : Morphological Evolution and Growth Mechanism of MC Carbide in Superalloy Mar-M247LC |
| Authors |
조창용(Chang Yong Jo),이재현(Je Hyun Lee),김두현(Doo Hyun Kim),서성문(Seong Moon Seo),최승주(Seung Joo Choe) |
| Abstract |
Morphological evolution and growth mechanism of MC carbide during solidification of Ni-base superalloy Mar-M247LC were investigated by directional solidification and quenching(DSQ) at various solidification rates. The stoichiometry of the MC type carbide was identified as (Hf, W, Ta)₂TiC₃ by EPMA. The morphology of the carbides showed a big difference between those formed at relatively low solidification rates of 0.8×10^(-6) m/s ∼ 2×10^(-6) m/s and high solidification rates of 5×10^(-6) m/s ∼ 15×10^(-6) m/s. As increasing the solidification rate, carbide morphology was transformed from equilibrium octahedron shape to complex dendritic shape. At low solidification rate, carbide growth occurred by a layered growth from steps on the {111} facets. When the carbide growth rate increased, some γ layer was incorporated into growing carbide to form a layered composite structure. The carbide morphologies were also determined according to positions and shapes of the mushy zone. |