Structural relaxation and recovery of bulk and ribbon glassy Pd₄₀Cu₃₀Ni₁₀P₂₀monitored by measurements of infralow-frequency internal friction

Abstract

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.

Usual stress relaxation in an ‘unusual’ Pd40Cu40P20 metallic glass

“…These regularities are: (i) strong dependence of stress relaxation kinetics on the degree of structural relaxation, (ii) specific isothermal relaxation law resulting in the straightening of the relaxation curves in the logarithmic coordinates and (iii) recovery of the ability to viscous flow of aged samples by quenching from the supercooled liquid state which can lead to even bigger relaxation as compared with the initial state. All observations taken together provide further evidence that the free volume is not a determinative in the viscous flow behavior of metallic glasses below the glass transition, in line with earlier findings [5,6,15,19].…”

“…It is important to investigate whether the annealing-induced loss of the deformation ability is truly irreversible or it can be recovered by a special heat treatment of glass. It was earlier found that the shear viscosity [3], stress relaxation ability [4,5], low frequency viscoelastic internal friction [6] as well as high-frequency shear modulus [7,8] of aged glassy Pd 40 Cu 30 Ni 10 P 20 can be recovered by rapid quenching from the supercooled liquid state (i.e. from temperatures T > T g ) indicating the recovery of structural relaxation lost in the course of preannealing.…”

Isochronal shear stress relaxation and recovery of bulk and ribbon glassy Pd40Cu30Ni10P20

“…At a quenching rate of 180 K/s, the recovery of torque relaxation remains partial although very significant. It is to be noted that the internal friction experiments [47] revealed just the opposite − aged bulk Pd 40 Cu 30 Ni 10 P 20 samples displayed bigger recovery as compared with the ribbons. Nonetheless, the obtained results suggest that structural relaxation and related homogeneous flow of metallic glasses can be recovered.…”

“…In this connection, one should first note the "reversible enthalpy relaxation" which is observed as recovery of the exothermal relaxation suppressed by preceding structural relaxation [41,42]. Besides that, the effects of partial recovery of the shear modulus [43], bending ductility at room temperature [44][45][46], relaxation of electrical resistance [34], recovery of the internal friction [47] and positron annihilation lifetime [48] by means of special heat or deformation treatment were reported. Finally, the effect of partial [49] or even complete [50] recovery of the ability to homogenous plastic flow in the course of creep measurements was found.…”

The recovery of the shear viscosity of thermally aged bulk and ribbon glassy Pd40Cu30Ni10P20 by rapid quenching from the supercooled liquid state

“…2, 3). The effects of the recovery of low‐frequency shear modulus 4, bending ductility at room temperature 5, 6, relaxation of electrical resistance 7, recovery of the internal friction 8 and positron annihilation lifetime 9 by means of heat treatment were reported. Finally, the effect of partial 10 or even complete 11, 12 recovery of the ability to homogeneous plastic flow in the course of isothermal creep 10, 11 and non‐isothermal stress relaxation measurements 12 was found.…”