Fusao Togashi1 and Taiji Nishizawa2
1Graduate School, Tohoku University, Sendai
Diffusion experiments were made on two-phase couples of ferrite ( α ) and austenite ( γ ) in Fe-C and Fe-C-M systems at 800°C. The interfacial carbon concentration in the γ phase was confirmed to deviate from equilibrium to a higher value during γ phase growth, and to a lower value during α phase growth. From the data on deviation of the interfacial composition, the mobility of the α/γ interface was evaluated. The results showed that the mobility of the α/γ interface was decreased remarkably by alloying addition of niobium, molybdenum or chromium. Such an effect of the alloying elements is quite analogous to that on the mobility of grain boundary in pure iron. This experimental fact implies that the effect of alloying elements on the mobility of the α/γ interface can be explained in terms of the solute drag or of other solute interactions on grain boundary migration.
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