Hypercooling of completely miscible alloys

Calorimetric measurements and undercooling investigations were performed on the high-melting, completely miscible binary systems (Co, Ni, Fe)-Pd. The alloys, characterized by phase diagrams with concavous liquidus and solidus lines, exhibit heat-of-fusion values considerably lower than calculated assuming ideal solution behavior. As a consequence, these metallic systems offer the possibility to achieve the hypercooling regime at a reduced extent of undercooling. Investigations on the undercoolability of the liquid alloys indicate the surmounting of the calculated hypercooling limit. Time-resolved radiation thermometry experimentally proved the appearance of complete isenthalpic solidification. Metallographic investigations of samples solidified from different levels of undercooling revealed the corresponding stages of microstructural evolution.