Self-diffusion in iron-based Fe–Mo alloys

Tracer diffusion coefficients of 59Fe and 99Mo in high-purity iron–molybdenum alloys containing up to 1.8 at.% molybdenum have been determined in the temperature range 823–1173 K by use of a serial sputter-microsectioning technique. The diffusion coefficient of iron (solvent) increases with increasing molybdenum content, whereas the diffusion coefficient of molybdenum (solute) decreases. The influence of magnetic transformation on the diffusion of iron in the iron–molybdenum alloys decreases with increasing molybdenum content, while that on the diffusion of molybdenum in the alloys is a maximum at about 0.8 at.% molybdenum. Analysis of jump frequency ratios shows that a vacancy is weakly bound by a molybdenum atom.