2024 年 64 巻 5 号 p. 826-835
To understand the interdiffusion of alloying elements in the α-Fe phase of the Fe–Cr–Mo and Fe–Cr–Si ternary systems, interdiffusion coefficients are determined. The main (
and 
, i: Cr and j: Mo or Si in the present study) and cross (
and 
) interdiffusion coefficients in the ternary systems were determined by the Whittle–Green method. From main interdiffusion coefficients in the ternary systems at 1073 K, the average value of 
was approximately 1.5 times higher than that of 
in the Fe–Cr–Mo system, while the average value of 
was 1.8 times higher than that of in the Fe–Cr–Si system. From the values of the ternary systems, Si has an accelerating effect than Mo on Cr diffusion in the α-Fe phase. Increasing the ratio of the Mo to Cr concentration has a suppressing effect on the respective Cr and Mo interdiffusion flux within the α-Fe phase. Increasing the concentration ratio of Mo to Cr suppresses the effect of Mo and Cr on the respective Cr and Mo interdiffusion fluxes within the α-Fe phase. Considering the temperature dependence, the Mo diffusivity is more sensitive than the Cr diffusivity. The cross interdiffusion coefficients, 
and 
, are positive and the values are insignificantly different in the Fe–Cr–Mo system, while 
and 
were negative. This study is beneficial to understand microstructure evolution in ferritic stainless steels at high temperatures.
