Annealing-induced enthalpy relaxation behavior of Ni-Pd-P-B bulk glassy type alloys

Annealing-induced structural relaxation behavior of Ni60Pd20P16B4 and Ni40Pd40P16B4 bulk glassy type alloys with maximum diameters above 10 mm was examined by measuring the temperature dependence of apparent specific heats in the as-spun and annealed states. The enthalpy relaxation (ER) occurs through a single stage. No distinct ER peak with a maximum phenomenon is observed at lower annealing temperatures (Ta) below about 523 (~Tg −65) K, while a significant ER peak is recognized after annealing near glass transition temperature (Tg). No ER peak phenomenon as a function of Ta in the Ta range up to Tg −65 K is due to the high stability to atomic rearrangement during annealing. The annealing-induced ER is independent of composition ratio of Ni/Pd and concluded to be a feature for multicomponent bulk glassy type alloys. The single stage ER behavior as a function of Ta is the same as that for typical bulk glass-type alloys in Zr-, La- and Pd-based systems. This ER behavior is different from the appearance of distinct two ER peaks for multicomponent amorphous alloys without glass transition. The same ER behavior over the wide Ni/Pd ratios for the present alloys provides an essential knowledge on the structural stability of bulk glassy type alloys.