Eur. Phys. J. Appl. Phys. 98, 8 (2023)
https://doi.org/10.1051/epjap/2022220266

Regular Article

Three mechanical relaxation modes associated with nanoscale structural heterogeneity in Pd_42.5Ni_7.5Cu₃₀P₂₀ fragile glass

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

^* e-mail: hao.wang.e4@tohoku.ac.jp

Received: 27 October 2022
Received in final form: 6 December 2022
Accepted: 13 December 2022
Published online: 24 January 2023

Abstract

The dynamic relaxation behavior of Pd_42.5Ni_7.5Cu₃₀P₂₀ metallic glass was studied at 173–563 K (∼0.98T_g) and at angular frequency 10⁻² to 10² rad s⁻¹. Master curves of 16-digit dynamic moduli at angular frequency 10⁻⁴ – 10¹² rad s⁻¹ were constructed and characterized by the stretched exponent relaxation function, which exhibits three discrete relaxation modes with different activation energies, i.e., α-relaxation (7.98 eV) associated with the cooperative motion of ∼5 atoms, slow β-relaxation (1.39 eV) associated with single atomic diffusion, and fast β-relaxation (0.25 eV) associated with rattling motion. These three modes were also detected as slope changes on the quasi-static creep compliance under an isochronal heating process, which was successfully reproduced by dynamic complex compliance using the dynamic moduli with fitting parameters related to the considerable inhomogeneous structural characteristics, elastic modulus and volume fraction, generated in the glass.