UNDERCOOLING INVESTIGATIONS AND HEAT-CAPACITY MEASUREMENTS ON PD-NI-PMELTS

The system Pd-Ni-P is well-known for its pronounced ability to form a metallic glass. Studies of the undercooling behaviour of the liquid al loy were carried out in a DTA facility applying the melt-fluxing techn ique at various cooling rates and overheating temperatures. This techn ique has been employed to seek the possibility of in situ investigatio ns of the heat capacity of the undercooled liquid. The measurements sh ow that crystallization can be avoided even for cooling rates as low a s 10 K/min if a sample is exposed several times to overheating tempera tures > 1270 K in the B2O3 flux. This allows for specific heat measure ments over a substantial undercooling range, if the fluxing method can be adapted for application in calibrated DTA devices. Heat capacities , C(p)(T), of the alloy in its undercooled liquid, glassy and crystall ized states were measured by standard differential scanning calorimetr y and compared with first results using differential thermal analysis techniques on fluxed samples.