SAXS study on crystallization of an amorphous Pd76Au6Si18 alloy

The crystallization behaviour of an amorphous Pd₇₆Au₆Si₁₈ alloy has been investigated mainly by means of small angle X-ray scattering measurements. The amorphous alloy crystallized to form MS-I phase with composition Pd₇₈Au₂₂ in the amorphous matrix, which later crystallized as MS-II. The crystallization kinetics of MS-I phase were analysed in the framework of conventional nucleation theory. It was suggested that the considerable number of nuclei of MS-I phase had been already formed in the as-quenched specimen and the remaining nucleation attained within the short period of isothermal ageing. The remarkable increase of the scattering intensity corresponded to the growth of MS-I phase, the kinetics of which were found to be controlled by the diffusion mechanism. The interdiffusion constant was obtained fromD=6.0×10¹⁵ exp (–420 kJ mol^–1/RT) m² sec^–1, which agreed fairly with the reported values.