Structural relaxation and recovery of bulk and ribbon glassy Pd40Cu30Ni10P20 monitored by measurements of infralow-frequency internal friction

Internal friction (IF) measurements (f = 0.05 Hz) on bulk and ribbon glassy Pd40Cu30Ni10P20 samples (production quenching rates 200 and ∼106 K s-1, respectively) upon thermal cycling within 370 K≤T≤Tg have been performed. It has been found that thermal cycling leads to a decrease of the IF and occurrence of related IF hysteresis as a result of (i) structural relaxation and (ii) relaxation of room-temperature plastic deformation arising upon preparation and handling of samples. Fast quenching (9-180 K s-1) of relaxed samples from the supercooled liquid state results in the IF recovery, which is strongly different for bulk and ribbon specimens. For the latter the IF remains smaller than that in the as-cast state, while quenched bulk samples display IF which is two to three times bigger as compared with the as-cast state. Possible reasons for such unusual behaviour are discussed