HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS
The transformation behavior of roller-quenched amorphous Pd0.82-xAuxSi0.18 and Pd0.835-xAuxSi0.165 alloys, where x or 0.10, after rapid heating to temperatures near to or above T sub g, is reported. Binary Pd0.18Si0.18 alloys crystallized to an f.c.c. phase without apparent composition segregation. The tendency to phase separate at T near T sug g, as manifested by small SAXS and large angle x-ray scattering and calorimetry, increased with increasing Au substitution. PD0.8Au.035Si0.165 alloy apparently phase separated by a nucleation and growth mechanism, with a growth rate limited by the melt viscosity, to form an f.c.c. phase dispersed in an amorphous phase which later crystallized. Pd0.74Au0.8Si0.18 alloy phase spearated initially to two melts each of which later crystallized in turn. The initial separation behavior was generally consistent with the predictions of the spinodal theory but with some deviation from Cahns linear relation.