Specific volume of glass-forming liquid Pd43Cu27Ni10P20 and related thermodynamic aspects of the glass transition

The volume change of the easy glass-forming alloy Pd43Cu27Ni10P20 was investigated continuously from the liquid to the vitreous state upon cooling at 10 K/min by means of the sessile drop technique. From the data obtained on density and thermal expansion, the specific volume as a function of temperature was deduced in the complete temperature range of the stable and the undercooled liquid as well as in the vitreous state for this alloy. Thus, the temperature dependence of the specific volume V(T) could be compared over the entire liquid range of a metallic glass former to that of the enthalpy H(T) obtained from preceding calorimetric measurements. A strong correlation between both thermodynamic functions becomes evident from this comparison and is interpreted on the basis of free-volume theory. The increase of the heat capacity at the glass transition can be explicitly explained by the creation and annihilation of free volume. (C) 2002 American Institute of Physics.