title: Effect of physical aging on Johari-Goldstein relaxation in La-based bulk metallic glass.
abstract: The influence of physical aging on the β relaxation in La60Ni15Al25 bulk metallic glass has been investigated by mechanical spectroscopy. The amplitude of the β relaxation (ΔG″) decreases while its relaxation time (τ(β)) increases during aging. We find that, as in organic glasses, the changes of ln (τ(β)) and ln (ΔG(max) ) are linearly correlated with ln (τ(β)) = b - a ln (G(max)″). This behavior is discussed in term of the asymmetric double-well potential (ADWP) model, with U and Δ the energies characterizing the ADWP. It is suggested that during aging the ratio U/Δ remains approximately constant, with a value close to the coefficient describing the linear correlation between ln (τ(β)) and ln (G(max)″)(U/Δ ~ a). Moreover, the evolution versus aging time of ΔG(max) can be described by a simple stretched exponential equation giving values of τ(aging) consistent with tan(δ) measurements during aging. The very similar behavior of the β relaxation during aging in metallic glasses and organic material strongly suggests a common nature for this relaxation.
authors.affiliation: Université de Lyon, CNRS, INSA-Lyon, MATEIS UMR5510, F-69621 Villeurbanne, France.
authors.forename: Jichao
authors.initials: J
authors.lastname: Qiao
authors.affiliation: Chemistry Division, Naval Research Laboratory, Code 6120, Washington DC 20375-5342, USA.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Casalini
authors.affiliation: Université de Lyon, CNRS, INSA-Lyon, MATEIS UMR5510, F-69621 Villeurbanne, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Pelletier