Revelation of the effect of structural heterogeneity on microplasticity in bulk metallic-glasses

Yang, Yong; Ye, Jianchao C.; J, Lu; Wang, Qing; Liaw, Peter K.

doi:10.1557/jmr.2010.0058

Cited by 16 publications

(5 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The β relaxation has been attributed to structural heterogeneity in metallic glasses and is linked to local movements of “weak spots” or “soft zones” (i.e., free volume, flow defects, or quasi-point defects, − liquid-like sites, , weakly bonded zones, , loose packing regions). The presence of structural heterogeneity in nano- or microscale domain has been verified in metallic glasses by transmission electron microscopy (TEM) and simulation method. − Unfortunately, the precise physical nature of the β relaxation is still far from being understood.…”

Section: Introductionmentioning

confidence: 99%

Relaxation of Bulk Metallic Glasses Studied by Mechanical Spectroscopy

2013

View full text Add to dashboard Cite

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. During aging experiments, the intensity decreases (as well as the τ β ) with a time dependence described well by a stretched exponential, with an exponent β aging independent of the driving frequency. Moreover, we find that the activation energy U β and the peak temperature T βp of the β relaxation follow the approximate relationship: U β ≈ 31.5RT βp (for driving frequency 1 Hz), indicating that the high temperature limit of the peak frequency is approximately the same for all the MGs investigated. Finally, the frequency separation of the α and β processes in the mechanical loss spectra for La-and Pd-based metallic glasses is tested against the prediction of the Coupling Model.

show abstract

Section: Introductionmentioning

confidence: 99%

Relaxation of Bulk Metallic Glasses Studied by Mechanical Spectroscopy

2013

View full text Add to dashboard Cite

show abstract

“…For example, Magagnosc et al [163] studied the irradiation effects on metallic glasses, wherein the pop-in tests can be employed to provide an indirect study of structural heterogeneity. Yang et al [164] have used spherical indentation to investigate the anelastic deformation in metallic glasses, as another way to probe the structural heterogeneity, which can certainly be combined with the pop-in statistical tests.…”

Section: Nanoindentation Pop-in As a Structural Probe In Bmgmentioning

confidence: 99%

Strength statistics of single crystals and metallic glasses under small stressed volumes

Gao¹,

Bei²

2016

Progress in Materials Science

View full text Add to dashboard Cite

It has been well documented that plastic deformation of crystalline and amorphous metals/alloys shows a general trend of "smaller is stronger". The majority of the experimental and modeling studies along this line have been focused on finding and reasoning the scaling slope or exponent in the logarithmic plot of strength versus size. In contrast to this view, here we show that the universal picture should be the thermally activated nucleation mechanisms in small stressed volume, the stochastic behavior as to find the weakest links in intermediate sizes of the stressed volume, and the convolution of these two mechanisms with respect to variables such as indenter radius in nanoindentation pop-in, crystallographic orientation, pre-strain level, sample length as in uniaxial tests, and others. Experiments that cover the entire spectrum of length scales and a unified model that treats both thermal activation and spatial stochasticity have discovered new perspectives in understanding and correlating the strength statistics in a vast of observations in nanoindentation, micro-pillar compression, and fiber/whisker tension tests of single crystals and metallic glasses.

show abstract

“…Apart from that, the constitutive behavior for the stress-displacement relation on a shear plane is not well defined for MGs. Unlike in crystalline materials with a periodic structure, the instantanous shear resistance of a MG alloy may vary with the location of a shear band even for a same shear displacement, which reflects the nano-scale structural heterogeneity intrinsic to MGs [35,36]. In such a case, the dimensionless factor 4 is of a statistic character.…”

Section: Formalism Of Energy Balance For Stable Shear Bandingmentioning

confidence: 99%

“…In such a case, the term H þ aD can be evaluated for different micropillars by assuming an average Poisson's ratio of w0. 35.…”

Section: Effect Of Alloy Compositionmentioning

confidence: 99%