Fragility, kinetic stability and phase separations in the undercooled state of bulk glass formers – a case study on metallic model systems

Abstract

Several Pd-base alloys display a large tendency for glass formation that renders them especially suitable for investigations concerning (metastable) equilibrium properties of the deeply undercooled liquid including the glass transition, since the detrimental interference of premature crystallization can be avoided rather easily compared to other alloy systems. Here, thermodynamic, dynamic, and transport properties were analysed and compared to an Al-rich marginal glass former in the context of a possible relation between fragility, thermodynamic excess and kinetic stability against crystallization. Additionally, the possibility for liquid-phase separation occurring in the undercooled state of bulk glass-forming alloys is analysed as a function of thermal history, and critically discussed with respect of alternative mechanisms that are often summarized as 'short-range ordering'.