Local heating associated with crack tip plasticity in Zr–Ti–Ni–Cu–Be bulk amorphous metals

Flores, Katharine M.; Dauskardt, Reinhold H.

doi:10.1557/jmr.1999.0642

Cited by 152 publications

(70 citation statements)

References 15 publications

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“…Our basic assumption is that the physics of this process involves the complicated interplay between local heating due to strain inhomogeneities and the developments of microvoids or microcracks within the shear bands. Temperatures can rise to high levels in front of these microdefects, as many workers have calculated and even measured to some success (see [15][16][17], for example). A physically-based account for these local temperatures, ahead of a moving crack tip, has been given by RICE and LEVY [17]:…”

Section: Discussionmentioning

confidence: 99%

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Rosenberg

Ashuach

Kreif³

2010

Matéria (Rio J.)

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The issue of adiabatic shearing is discussed in this work and a new interpretation is given to some failure phenomena which are usually termed as adiabatic shears. We propose that only a few materials undergo a truly inherent failure which is due to thermal softening at the shearing zone and that the interplay between microvoids, cracks and narrow shear bands should be taken into account through the temperature rise at the front of advancing cracks. Also, the size of the plastic zone ahead of a crack plays an important role in determining the brittleness of a given specimen and should be taken into account when specimens of different sizes are tested. Experimental results for several alloys in the Kolsky bar system support our approach.Keywords: Kolsky bar, SHPB, adiabatic shear banding. INTRODUCTIONAdiabatic shear banding is one of the major failure mechanisms of solids subjected to high rate loading. Extensive research on this subject has been conducted over the past 50 years, both experimentally and theoretically, much of which is summarized in BAI and DODD [1]. The most common explanation of this dynamic instability is based on the competing tendencies of the solid to strengthen at high strains (and strain rates) and, on the other hand, to soften with the temperature increase under adiabatic loading conditions. Although many materials seem to behave accordingly, the basic mechanism which causes this softening is still unresolved. Recent work on the subject is focused on the basic physics behind this process, as can be found in [2-5], for example. These works emphasize the link between adiabatic shearing and ductile fracture by the coalescence of microvoids, since the shear zones act as precursor sites for eventual failure by cracks (see [2]). GIOVANOLA [3,4] conducted a careful experimental study on 4340 steel specimens, in order to follow the evolution of strain localization and failure which he finds to proceed in two stages. He found that the first stage of localization (deformed bands) results in the formation of local perturbations for the strain field, such as machining marks. These perturbations grow as a result of the imbalance between strain hardening and thermal softening. In the second stage, softening is due to the nucleation and growth of microvoids, leading to the shear fracture within the band. GIOVANOLA [3,4] suggested that this process can take place under other conditions, including quasi-static loading. He also emphasized the role of the compressive stress which acts on the shear plane to reduce the microvoid nucleation process.FLOCKHART et al.[5] used numerical simulations to follow the shear band in dynamically compressed specimen, by analyzing the loci of velocity discontinuities within the specimen. They also claim that "the distinction between shear fracture and adiabatic shear failure is not clear", and that "material susceptibility to adiabatic shear alone does not guarantee that failure occurs by this mechanism, as shear fracture may intervene". This interplay between shear...

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Section: Discussionmentioning

confidence: 99%

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Rosenberg

Ashuach

Kreif³

2010

Matéria (Rio J.)

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“…The first direct experimental evidence of the limited extent of adiabatic heating in the plastic zone ahead of a Mode I crack under nominal loading rates was also determined [8]. Several crack growth sequences were captured using a thermal imaging system as the crack propagated and arrested.…”

Section: Stress State and Temperature Effects On Shear Band Formationmentioning

confidence: 99%

Fundamental Mechanisms of Deformation and Fracture in High-Strength Bulk Metallic Glass Alloys and Their Composites

Dauskardt¹

2001

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“…Bulk Metallic Glasses [1] and their Composites [2] have emerged [3] as competitive structural engineering material [4] during last two decades and have attracted the attention of several major research clusters [5]- [19] around the globe to further investigate into scientific reasons behind their formation [20], microstructural evolution [21], property development and structure-property relationship [22] [23]. Main areas of research activity have been focused around probing into mechanical properties and their improvement as these materials have high hardness, strength and elastic strain limit but suffer from lack of ductility which make them brittle and they fail abruptly [24] [25] under the application of tensile and impact loading.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Solidification Parameters during Zr Based Bulk Metallic Glass Matrix Composite’s (BMGMCs) Additive Manufacturing

Rafique¹

2018

ENG

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After a silence of three decades, bulk metallic glasses and their composites have re-emerged as a competent engineering material owing to their excellent mechanical properties not observed in any other engineering material known till date. However, they exhibit poor ductility and little or no toughness which make them brittle and they fail catastrophically under tensile loading. Exact explanation of this behaviour is difficult, and a lot of expensive experimentation is needed before conclusive results could be drawn. In present study, a theoretical approach has been presented aimed at solving this problem. A detailed mathematical model has been developed to describe solidification phenomena in zirconium based bulk metallic glass matrix composites during additive manufacturing. It precisely models and predicts solidification parameters related to microscale solute diffusion (mass transfer) and capillary action in these rapidly solidifying sluggish slurries. Programming and simulation of model is performed in MATLAB ® . Results show that the use of temperature dependent thermophysical properties yields a synergic effect for multitude improvement and refinement simulation results. Simulated values proved out to be in good agreement with prior simulated and experimental results.

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Local heating associated with crack tip plasticity in Zr–Ti–Ni–Cu–Be bulk amorphous metals

Cited by 152 publications

References 15 publications

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Fundamental Mechanisms of Deformation and Fracture in High-Strength Bulk Metallic Glass Alloys and Their Composites

Simulation of Solidification Parameters during Zr Based Bulk Metallic Glass Matrix Composite’s (BMGMCs) Additive Manufacturing

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