Diffusion mechanism of iron in ternary (Ni,Fe)Al alloys with B2-structure

We have directly determined the atomistic diffusion mechanism of iron atoms in Ni40Fe10Al50 and Ni45Fe5Al50 intermetallic B2 alloys with quasielastic Mِssbauer spectroscopy. Our measurements show a clear nearest-neighbour jump of Fe with an activation energy of 4.0(3) eV for both compositions in agreement with recent tracer diffusion results for Ni diffusion in the NiAl compound with B2 structure. Direct next-nearest neighbour jumps can be definitely excluded as a jump mechanism for iron. Jump frequencies and the diffusion coefficient of iron have been measured. The diffusion of iron in ternary (Ni,Fe)Al is about two times faster than diffusion of nickel in the Ni50Al50 alloy.