Thermodynamic properties of Pd-based glass-forming alloys

Undercooled liquids of the easy glass-forming alloys Pd-Ni-P and Pd-Cu-Ni-P (Pd40Ni40P20, Pd40Ni10Cu30P20, Pd43Ni10Cu27P20) have an extra-ordinary sta bility against crystallization allowing for direct calorimetric measurement s of this metastable state. The liquid alloys can be undercooled consistent ly into the glassy state at moderate cooling rates of about 0.2 K/s and hea t capacity measurements have been performed covering the undercooling regim e from the melting temperature to the glass transition temperature. The the rmodynamic functions of the alloys in dependence on temperature were evalua ted. The isentropic temperature, T-K, Often interpreted as the low temperat ure limit of the liquid state, was determined from the excess entropy. Enth alpy relaxation experiments show that the addition of Cu leads to an increa se in the fragility of the Pd-based alloys. (C) 1999 Elsevier Science B.V. All rights reserved.