On the stability limits of the undercooled liquid state of Pd-Ni-P

The easy glass-forming metallic alloy Pd-Ni-P exhibits an exceptional resistance against crystallization in the deeply undercooled liquid state. In the present work, the absence of crystallization was utilized to equilibrate bulk amorphous samples at different temperatures below the glass transition by extended isothermal annealing. Specific heat data and equilibrium viscosity data could be obtained in the glass transition region. From density and volume expansion measurements the thermal expansion coefficient of the undercooled liquid could be derived. The free volume frozen-in at typical cooling rates could be determined to be in the order of 0.3%. The results are discussed with regard to stability criteria of the undercooled liquid state.