Strain-driven Kovacs-like memory effect in glasses.

Studying complex relaxation behaviors is of critical importance for understanding the nature of glasses. Here we report a Kovacs-like memory effect in glasses, manifested by non-monotonic stress relaxation during two-step high-to-low strains stimulations. During the stress relaxation process, if the strain jumps from a higher state to a lower state, the stress does not continue to decrease, but increases first and then decreases.

Detecting the exponential relaxation spectrum in glasses by high-precision nanocalorimetry.

Nonexponential relaxations are universal characteristics for glassy materials. There is a well-known hypothesis that nonexponential relaxation peaks are composed of a series of exponential events, which have not been verified. In this Letter, we discover the exponential relaxation events during the recovery process using a high-precision nanocalorimetry, which are universal for metallic glasses and organic glasses.

Correlation between High Temperature Deformation and β Relaxation in LaCeBased Metallic Glass.

Hightemperature deformation around the glass transition temperature T and the dynamic mechanical behavior of LaCeAlCo metallic glass were investigated. According to dynamic mechanical analysis (DMA) results, LaCeAlCo metallic glass exhibits a pronounced slow β relaxation process. In parallel, strainrate jump experiments around the glass transition temperature were performed in a wide range of strain rate ranges.

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

We study the mechanical relaxation spectrum of Pd42.5Ni7.5Cu30P20 metallic glass.

Effect of physical aging on Johari-Goldstein relaxation in La-based bulk metallic glass.

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)″).

Characteristics of the structural and Johari-Goldstein relaxations in Pd-based metallic glass-forming liquids.

The dynamics of Pd-based metallic glass-forming liquids (Pd(40)Ni(10)Cu(30)P(20), Pd(42.5)Ni(7.5)Cu(30)P(20), Pd(40)Ni(40)P(20), and Pd(30)Ni(50)P(20)) was studied by mechanical spectroscopy and modulated differential scanning calorimetry (MDSC).

Relaxation of bulk metallic glasses studied by mechanical spectroscopy.

The relaxational dynamics in metallic glasses (MGs) is investigated by using mechanical spectroscopy. The spectra show that in MGs there are two relaxations: (i) the α relaxation, linked to the glass transition, as observed in other classes of amorphous materials; and (ii) the β relaxation, well observed below the glass transition, with an intensity strongly dependent on the MG composition, the nature of which has been linked to the local microstructure of MGs. For the investigated MGs we find that the intensity and relaxation time of the β relaxation depends, in a reproducible fashion, on the thermal history of the samples.