THERMODYNAMICS OF UNDERCOOLED LIQUIDS AND ITS APPLICATION TO AMORPHOUS PHASE-FORMATION

The thermodynamic functions of undercooled liquids and amorphous phase s can be determined most favourably by utilizing the CALPHAD method. T herefore, calorimetric and e.m.f. investigations have been employed on amorphous phases. The results demonstrate the metastable state of the amorphous alloys, and show that the thermodynamic functions of the un dercooled liquid are strongly influenced by an excess specific heat, w hich stabilizes the undercooled liquid at low temperatures. The excess specific heat reflects the chemical and topological ordering of the l iquid on cooling, which can result in the occurrence of an inverse mel ting point and in phase separation in the amorphous state. In addition , e.m.f. measurements confirm the validity of the Gibbs-Duhem equation . Thus phase diagrams of metastable phases can be calculated for under cooled liquids and amorphous phases which can be used to determine the concentration ranges for amorphous phase formation by various prepara tion methods.