Fast and slow dynamics in Pr60 Ni10 Cu20 Al10 melts as seen by neutron scattering

We present experimental results on the fast Β and slow α relaxational dynamics observed through incoherent quasielastic neutron scattering from Pr60 Ni10 Cu20 Al10 melts. The density correlation function, measured over a range of temperatures, shows a clear two-step relaxation process. The critical or crossover temperature, Tc, evaluated from the asymptotic scaling function of the mode-coupling theory was found to be at 620±5 K. The correlation decay is not exponential, being extended over a far wider time range. In addition, the stretched exponent Βq was found to be independent of temperature and momentum transfer (q). The self-diffusivity is an order lower compared with that observed in simple metallic liquids at their melting temperature. © 2008 American Institute of Physics.