The impurity diffusion of Zn was investigated by using the radiotracer technique and the isotope, 65Zn. The Zn was chosen with the aim of simulating Al diffusion; for which no feasible radio-isotope was available. It was found that the diffusivity of Zn was slightly higher than that of Fe. Most of the measurements were performed in the B2-structure regions of the phase diagram, plus some in the A2-structure region and a few in the D03-structure region. There were 2 ordering transitions in Fe3Al; between A2 and B2, and between B2 and D03. Both of them led to an increase in the activation enthalpy for diffusion in the phase having the higher degree of order. With increasing Al content, the

activation enthalpy for diffusion increased, even though the melting point decreased significantly. The data (table 43, figure 15) could be described by:

65Zn in Fe74.5Al25.5 (A2/B2):     D (m2/s) = 1.8 x 10-4 exp[-2.29(eV)/kT]

M.Eggersmann, H.Mehrer: Philosophical Magazine A, 2000, 80[5], 1219-44

Table 42

Diffusivity of 114mIn in Fe3Al

Figure 12

Diffusivity of 59Fe in Fe74.5Al25.5

Figure 13

Diffusivity of H in Fe3Al-Based (5Cr, 0.1Zr, 0.05B) Alloy

Figure 14

  Diffusivity of 114mIn in Fe74.5Al25.5

Table 43

Diffusivity of 65Zn in Fe3Al