Table 4.
The structural parameters and chemical composition of possible variants of the ω′ and θ′ carbides. The electron diffraction patterns of the ω′-Fe6C2 (ω′-Fe3C) and θ′-Fe12C4 (θ′-Fe3C) are the same with that of the ω-Fe3C.
| Metastable carbide | Variant composition | Notes |
|---|---|---|
|
ω′, orthorhombic aω′ = 4.033 Å, bω′= 2.47 Å, cω′ = 6.986 Å |
ω′-Fe6C | C atoms at different (001) atomic planes |
| ω′-Fe6C | ||
| ω′-Fe6C2 (ω′-Fe3C) | ||
|
θ′, orthorhombic aθ′ = 4.033 Å, bθ′= 4.94 Å, cθ′ = 6.986 Å |
θ′-Fe12C2 (θ′-Fe6C) | C concentration varies at different (001) atomic planes |
| θ′-Fe12C3 (θ′-Fe4C) | ||
| θ′-Fe12C4 (θ′-Fe3C) |