The atomistic diffusion mechanism of Fe atoms in Ni40Fe10Al50 and Ni45Fe5Al50 intermetallic B2 alloys was determined directly via quasi-elastic Mössbauer spectroscopy. The measurements revealed a clear nearest-neighbour jump of Fe, with an activation energy of 4.0eV 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 could be definitely excluded as a jump mechanism for Fe. Jump frequencies and the diffusion coefficient of Fe were measured. The diffusion of Fe in ternary (Ni,Fe)Al was about two times faster than diffusion of Ni in the Ni50Al50 alloy.

Diffusion Mechanism of Iron in Ternary (Ni,Fe)Al Alloys with B2-Structure. M.Rennhofer, B.Sepiol, W.Löser, G.Vogl: Intermetallics, 2003, 11[6], 573-80