The static and dynamic specific heat of undercooled metallic liquids

Abstract Experimental data on the equilibrium (static) specific heat of undercooled metallic liquids are presented that are representative for different classes of constitutive behavior ranging from pure noble metals to alloy systems that are characterized by strong tendencies to form self-associates or associates of unlike atoms in the liquid state. Deviations from a monotonous course of the specific heat that are expected to occur as a characteristics for an accelerated evolution of ordering processes in the undercooled melt excluding the crystalline state are discussed and selected examples are compared to the results of theoretical model calculations. Besides these measurements of the static heat capacity, modulation calorimetry provides the possibility to detect characteristic times of slow relaxation modes of the deeply undercooled melt that are coupled to the occurrence of the glass transition upon continued cooling. Nevertheless, such data are only scarcely available for metallic glass formers and have not yet been quantitatively analyzed with respect to the intrinsic relaxation times of the deeply undercooled liquid state. In this contribution, modulated temperature calorimetry measurements on bulk glass forming Pd alloys are reported. The results that reveal the typical behavior known for dissipative systems are evaluated with respect to the temperature dependence of the mean relaxation time as well as the shape of the relaxation time spectrum in the vicinity of the structural glass transition.