Diffusive motions in crystalline AlCuNi by neutron quasielastic scattering

Quasi-elastic neutron scattering experiments have been performed on the Al5 0Cu35Ni15 alloy on the IRIS spectrometer at ISIS and on the MIBEMOL spectro meter at LLB, Saclay. The aim was to investigate if atomic hopping motions are restricted to occur in systems with quasicrystalline local order. It is found that frequent jumps of Cu and Ni atoms between different interstitia l lattice positions on the time scale 1-100 ps are taking place in this all oy at high temperature, This is the same time scale that has been found ear lier in quasicrystals and it suggests that this kind of motion is likely to take place in any metallic alloy at high temperature and that it is not a special property of quasicrystals. (C) 2001 Elsevier Science B,V. All right s reserved.