Viscoelasticity of Cu- and La-based bulk metallic glasses: Interpretation based on the quasi-point defects theory

Abstract

The dynamic mechanical relaxation of metallic glasses is closely associated with the physical and mechanical properties. In the current work, the dynamic mechanical relaxation behaviors of Cu46Zr45Al7Y2 and La65Al14(Cu5/6Ag1/6)11(Ni1/2Co1/2)10 bulk metallic glasses are investigated by mechanical spectroscopy. In general, metallic glasses display two relaxation modes: main ( ) relaxation and the slow secondary ( ) relaxation. The α relaxation is linked to the dynamic glass transition phenomenon and viscous flow while the slow relaxation is associated with many fundamental issues, such as diffusion and glass transition phenomenon. The experimental study shows La65Al14(Cu5/6Ag1/6)11(Ni1/2Co1/2)10 bulk metallic glass displays a noticeable slow relaxation. Contrarily, the Cu46Zr45Al7Y2 bulk metallic glass relaxation process takes the form of an "excess wing". In the framework of quasi-point defects (QPD) theory, the dynamic mechanical response of the metallic glasses is discussed.

Influence of Microalloying Process on Dynamic Mechanical Relaxation of ZrCo-Based Amorphous Alloy

“…Figure 7 also shows that the exponent is in the range of 0.5, as also reported in other works related to glassy alloys [43]. For Advances in Materials Science and Engineering evaluation of dynamic mechanical behavior of MGs, it is also possible to apply the theory of quasi-point defects (QPDs) [44]. In this theory, the defect concentration of glassy structure is quantified and correlated to the normalized loss modulus:…”

Effect of minor addition on dynamic mechanical relaxation in ZrCu-based metallic glasses

“…By the same method, the activation energy E  of Zr50Cu34Ag8Al8 is 5.858 eV. The result is in good agreement with other CuZr-based metallic glass systems [38,41] .This value of the apparent activation energy of the -relaxation in the super-cooled liquid region corresponds to a liquid fragility of 𝑚 43.…”

“…The loss factor, tan𝐸"/𝐸 , is related to the atomic or molecular mobility of glassy materials [38] .…”

Reversible anelastic deformation mediated by β relaxation and resulting two-step deformation in a La60Ni15Al25 metallic glass

“…Its characteristic time decreases following the Arrhenius law as temperature increases, eventually becoming undetectable at the experimental timescale. We also observed that the stress decay caused by the  relaxation during deformation is only about 5%, which is far less than the anelastic component (>30%) of the amorphous solids in some previous literature [28,41]. Therefore, part of the anelastic component should be derived from the contribution of the second deformation process controlled by the  relaxation.…”