Facilitation and correlation of flow in metallic supercooled liquid

Zhang, Meng; Liu, Lin; Wu, Yue

doi:10.1063/1.4826318

Cited by 17 publications

(6 citation statements)

References 31 publications

(44 reference statements)

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“…1a) of materials increases at lower temperatures, showing the strengthening behavior at T > 20 K. On the other hand, the increase in the critical shear stress will in turn improve the dilatation ability of STZs, since the STZ has the nature of shear thinning or -dilatation due to the disordered structure. This picture is supported by the common observation that metallic glasses with higher strengths are always accompanied by a more significant softening to cracking [53][54]. Therefore, the STZ at lower temperatures becomes more inclined to dilatation operations, macroscopically corresponding to the decrease in the critical normal tensile stress r 0 (Fig.…”

Section: Discussionmentioning

confidence: 54%

Cryogenic-temperature-induced transition from shear to dilatational failure in metallic glasses

et al. 2014

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Section: Discussionmentioning

confidence: 54%

Cryogenic-temperature-induced transition from shear to dilatational failure in metallic glasses

et al. 2014

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“…These fluctuation are not completely independent from their neighbors, but become correlated over short length scales that then grow as the flow proceeds much like a rejuvenation front (16). This correlation allows the glass to differentially deform different regions to develop shear banding patterns like those in the laboratory (3,4,49,50). We have marked the shear bands observed in our simulation in Fig.…”

Section: Resultsmentioning

confidence: 59%

Dynamical theory of shear bands in structural glasses

Wisitsorasak

Wolynes

2017

Proc. Natl. Acad. Sci. U.S.A.

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The heterogeneous elastoplastic deformation of structural glasses is explored using the framework of the random first-order transition theory of the glass transition along with an extended mode-coupling theory that includes activated events. The theory involves coupling the continuum elastic theory of strain transport with mobility generation and transport as described in the theory of glass aging and rejuvenation. Fluctuations that arise from the generation and transport of mobility, fictive temperature, and stress are treated explicitly. We examine the nonlinear flow of a glass under deformation at finite strain rate. The interplay among the fluctuating fields leads to the spatially heterogeneous dislocation of the particles in the glass, i.e., the appearance of shear bands of the type observed in metallic glasses deforming under mechanical stress.glass transition | mode-coupling theory | strength of materials | shear bands W hether and how glasses flow have been fascinating questions for a long time. In the absence of stress, a glass seems to be static on human timescales, the molecules being arranged like a frozen snapshot of the liquid state. In fact, molecules in the glass are constantly moving and the glass itself is not in a state of equilibrium. Even without applied stress, molecules do change their locations through rare, activated events. These events occur at a rate that is both spatially and temporally heterogeneous. Glasses therefore continue to evolve, albeit slowly, as they approach equilibrium and age (1). These activated events are accelerated by applied stresses and typically will act to reduce the stress so that under sufficient stress the glass will not just deform elastically but visibly flow and possibly break. The deformations caused by stress are not uniform in the glass, but appear to concentrate in shear bands (2-4). In this work, we show how shear bands arise dynamically by the coupling of the activated dynamics of configurationally rearranging regions with elastic strain transport. The heterogeneous activated dynamics of glasses under mechanical deformation are described using a first-principle framework based on the random first-order transition (RFOT) theory along with an extended mode-coupling theory that describes how activated events are coupled in space and time (5-10).The random first-order transition theory of glasses is a microscopic theory that has already provided a unified quantitative description of large number of aspects of the behavior of supercooled liquids and structural glasses (11). The theory brings together two seemingly disparate aspects of glass formation: the breaking of replica symmetry that occurs in mean-field models and a theory of the activated events that tend to locally restore replica symmetry in systems with short-range interactions (7,8,(12)(13)(14). In mean-field models, there is a special temperature T d at which a dynamical transition to immobility occurs discontinuously. Above this temperature the system is well described by ordinary mode-coupli...

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“…Similar long-range stress effect also applies to the softening effect in the collective activation of dislocations (Wang et al, 2018a;Zaiser and Hahner, 1997). Actually, phenomenological flow models which take into account the collective effect in the plastic deformation of MGs and crystalline materials have already been established (Zaiser and Hahner, 1997;Zhang et al, 2013). By incorporating the collective effect, the strain rate softening phenomenon in the plastic deformation of both crystalline and amorphous materials can be predicted.…”

Section: Homological Softening Dynamics In the Glassy And Crystallizementioning

confidence: 89%