Mechanical Relaxation of Metallic Glasses: An Overview of Experimental Data and Theoretical Models

Abstract

Relaxation phenomena in glasses are a subject of utmost interest, as they are deeply connected with their structure and dynamics. From a theoretical point of view, mechanical relaxation allows one to get insight into the different atomic-scale processes taking place in the glassy state. Focusing on their possible applications, relaxation behavior influences the mechanical properties of metallic glasses. This paper reviews the present knowledge on mechanical relaxation of metallic glasses. The features of primary and secondary relaxations are reviewed. Experimental data in the time and frequency domain is presented, as well as the different models used to describe the measured relaxation spectra. Extended attention is paid to dynamic mechanical analysis, as it is the most important technique allowing one to access the mechanical relaxation behavior. Finally, the relevance of the relaxation behavior in the mechanical properties of metallic glasses is discussed.

Modeling of the Sub-Tg Relaxation Spectrum of Pd42.5Ni7.5Cu30P20 Metallic Glass

“…This is not the case in other metallic glasses in which well relaxed states only show a low-temperature excess wing of the primary relaxation 9,17,34 . The presence of sub-Tg mechanical relaxation with significant intensity is found in most Pd-based metallic glasses and it is probably related to the good ductility shown by this family of amorphous metals 36 .…”

O Viskoelastičnim Svojstvima Asfaltnih Mešavina

“…1. This type of studies is widely recognized and important in the analysis of metallic glasses [1,2], asphalt mixtures [3,4] and dental materials [5,6]. However, it must be noted that due to the jump, it is not easy to describe both creep and recovery behavior with the accepted constitutive axiom and the same set of parameters.…”

Effect of Ultrasonic Treatment in the Static and Dynamic Mechanical Behavior of AZ91D Mg Alloy

“…If the strain amplitude values are increase, higher than the material critical strain (εcr), the internal friction becomes strain-dependent and increases exponentially. The strain-independent internal friction is the result of reversible movements of dislocation and microscopic yielding [14] around the initial pinned positions and is associated to the values obtained by the application of Equation (8) (8) where ρ is the dislocation density and l is the mean length of dislocation between the weak pinning points [15]. Dislocation damping can be enhanced by thermal activation.…”

“…These two factors are correlated to the material complex modulus (E*), that can be defined by a dissipated energy part (loss modulus, E″) and a stored energy part (storage modulus, E′) according to Equation (5). The ratio between the dissipated and stored energies is the internal friction (Q −1 ) of the material, which can be determined by the use of Equation (6) [8]:…”