Mechanism and kinetics of dissolution of Cr₃C₂ in iron

Conclusions

• 1. A study was made of the dissolution mechanism of Cr₃C₂ in iron. It was established that the reaction of orthorhombic chromium carbide with iron begins at 350–400°C and, up to the beginning ofα→γ transformation, manifests itself in diffusional exchange of iron and chromium atoms and in the formation of a special orthorhombic carbide. In the temperature range of existence ofγ-iron, the dissolution of the orthorhombic carbide is preceded by its recrystallization into the hexagonal form and the latter's enrichment in iron to a content close to the solubility limit of iron.

• 2. Up to a temperature of ∼1050°C, the carbide dissolution process is limited by the (CrFe)₃C₂→ (CrFe)₇C₃ transformation. Above 1050°C, diffusion becomes the link controlling the rate of the process.

• 3. Orthorhombic chromium carbide dissolves quite rapidly in iron, and can therefore be employed as an alloying addition.