Low Speed Crack Propagation via Kink Formation and Advance on the Silicon (110) Cleavage Plane

Kermode, James R.; Gleizer, Anna; Kovel, Guy; Pastewka, Lars; Csänyi, Gábor; Sherman, Dov; Vita, Alessandro De

doi:10.1103/physrevlett.115.135501

Cited by 31 publications

(36 citation statements)

References 32 publications

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“…Possible resolutions include: (1) improved interatomic potentials, e.g. coarse-grained from electronic structure in the bond order potential formulation [126] or automatically constructed using machine learning (ML) from a database of reference quantum mechanical (QM) configurations [10,15], (2) concurrent multiscale approaches where localised regions are modelled with QM precision within a non-uniform precision embedding scheme [17] enabling direct simulation of complex crack tip chemistry [97].…”

Section: Atomistic Simulationsmentioning

confidence: 99%

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

et al. 2018

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Hydrogen embrittlement is a complex phenomenon, involving several lengthand timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement.

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Section: Atomistic Simulationsmentioning

confidence: 99%

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

et al. 2018

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“…Figure 4 depicts the stress intensity factor at failure K If versus the specimen width W and the comparison with other works. [20,42] To investigate the behavior of the stress intensity factors at fracture on the continuum side, the values of K If are normalized with respect to the K If obtained for the largest specimen W = 198.41 nm and compared in Figure 5. Since K If is evaluated at fracture, it can be regarded as a good approximation of the fracture toughness, which shows a clear scale independence.…”

Section: Discussionmentioning

confidence: 99%

On the Crack‐Tip Region Stress Field in Molecular Systems: The Case of Ideal Brittle Fracture

Gallo

2019

Advcd Theory and Sims

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Continuum-based fracture mechanics breaks down at the nanoscale where the discrete nature of atoms cannot be neglected. Intriguingly, this work shows that the concept of stress intensity factor is still valid if the atoms are modeled. Molecular statistics simulations are conducted on single-edge cracked samples of ideal brittle silicon, varying the size until few nanometers. The local virial stress, derived as the functional derivative of the free energy of a molecular system with respect to the deformation tensor, is used as a measure of the mechanical stress at the atomic level. Then, stress intensity factor at failure is evaluated. The results show that regardless of the size, the atomistic stress field varies according to the classical 1/r 0.5 relation, and discrete stress intensity factors can be derived for all the geometries. Continuum values, in contrast, fail to describe the fracture when the length of the singular stress field is smaller than 4-5 times the fracture process zone. Thus, this work shows that the stress intensity factor from atomic stress may be useful to describe the fracture criterion at extremely small dimensions, provided that virial stress is accepted as a representation of mechanical stress at the atomic level.

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“…Molecular dynamics simulations explained this threshold as a consequence of a localized phase transformation in the vicinity of the crack tip [13] that delays the fracture initiation. However, a recent work suggested that the velocity gap should not be considered as an universal indication, since an extremely low speed (in 100 m/s speed range) cleavage along (110) can stably take place via kink formation and advance under a suitable temperature and some specific loading conditions [14]. This new finding reveals that the external conditions need to be carefully considered when investigating the fracture in silicon.…”

mentioning

confidence: 97%

Disturbance and recovery in high speed (110) cleavage in single crystalline silicon

Zhao

Wang

Maynadier

et al. 2018

Journal of the European Ceramic Society

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Stress perturbations and material defects can significantly affect the fracture initiation and propagation behaviors in brittle materials. In this work, we show that (110) [110] cleavage in silicon deflects onto (111) plane in the presence of contact stresses. The deflection is however not permanent as the crack returns to the (110) plane after a certain length of propagation, even in the case where the crack velocity is up to 78% of the Rayleigh wave speed. The recovery behavior indicates that the (110) [110] cleavage is invariably prevailing when perpendicular to the maximum stress. Following this indication, it can be concluded that the observed (110) [110]-(111) deflection in previous literature is most likely driven by the external disturbance rather than the crack velocity induced toughness evolution. We also highlight that the extra energy for the (110) recovery is minimized at the expense of a large propagation distance upon the plane switch.

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Low Speed Crack Propagation via Kink Formation and Advance on the Silicon (110) Cleavage Plane

Cited by 31 publications

References 32 publications

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

On the Crack‐Tip Region Stress Field in Molecular Systems: The Case of Ideal Brittle Fracture

Disturbance and recovery in high speed (110) cleavage in single crystalline silicon

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