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. ©1996 American Institute of Physics.