PHASE SEGREGATION AND CRYSTALLIZATION IN THE AMORPHOUS ALLOY NI70MO10P20

Structural evolution of the amorphous alloy Ni70Mo10P20 has been studi ed by x-ray diffraction, and by following transmission and high-resolu tion electron microscopy annealing both above and below the glass-tran sition temperature. When annealed above this temperature, the amorphou s phase undergoes segregation into regions about 100 nm in size having different chemical composition. Diffraction from such samples produce s diffuse rings, and the scattering vector corresponding to the maximu m intensity varies from point to point within the interval of 4.88 to 4.78 nm(-1). When occurring between the glass-transition and crystalli zation temperatures, crystallization produces groups of nanocrystals, 20-30 nm in size, which are in direct contact with one another and for m a polymorphic mechanism. The crystallization mechanism changes when the annealing temperature is brought below the glass-transition point. At these temperatures the amorphous matrix crystallizes entectically with formation of eutectic colonies. (C) 1998 American Institute of Ph ysics. [S1063-7834(98)00109-9].