Ductile versus brittle behaviour of crystals

Rice, James R.; Thomson, Robb

doi:10.1080/14786437408213555

Cited by 1,527 publications

(418 citation statements)

References 20 publications

Supporting

Mentioning

410

Contrasting

Unclassified

Order By: Relevance

“…[42,43,82] The premise of this model is that near-crack-tip stress (and local stress intensity) is modeled by coupling a small array of dislocations, spaced in equilibrium with the crack tip elastic stress field, and including Rice-Thompson dislocation emission. [86] These dislocations shield the singular-elastic stress at the crack tip. Surrounding-tip plasticity is represented by a superdislocation located at the centroid of the highly strained continuum plastic zone, and related to stress intensity.…”

Section: E Threshold For Heacmentioning

confidence: 99%

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

View full text Add to dashboard Cite

Hydrogen environment-assisted cracking (HEAC) of Monel K-500 is quantified using slow-rising stress intensity loading with electrical potential monitoring of small crack propagation and elastoplastic J-integral analysis. For this loading, with concurrent crack tip plastic strain and H accumulation, aged Monel K-500 is susceptible to intergranular HEAC in NaCl solution when cathodically polarized at À800 mV SCE (E A , vs saturated calomel) and lower. Intergranular cracking is eliminated by reduced cathodic polarization more positive than À750 mV SCE . Crack tip diffusible H concentration rises, from near 0 wppm at E A of À765 mV SCE , with increasing cathodic polarization. This behavior is quantified by thermal desorption spectroscopy and barnacle cell measurements of hydrogen solubility vs overpotential for planar electrodes, plus measured-local crevice potential, and pH scaled to the crack tip. Using crack tip H concentration, excellent agreement is demonstrated between measurements and decohesion-based model predictions of the E A dependencies of threshold stress intensity and Stage II growth rate. A critical level of cathodic polarization must be exceeded for HEAC to occur in aged Monel K-500. The damaging-cathodic potential regime likely shifts more negative for quasi-static loading or increasing metallurgical resistance to HEAC.

show abstract

Section: E Threshold For Heacmentioning

confidence: 99%

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…These together suggest that the 0.27 MPa m 1/2 stress intensity above in fact may not even be suciently high to emit the ®rst dislocation. This is further reinforced by Rice and Thomson's [35] original calculation of the local stress intensity, k Ie , for dislocation emission in copper. This value is given as 0.32 MPa m 1/2 .…”

Section: Superlayer Induced Film Decohesionmentioning

confidence: 97%

Nanoindentation-induced defect–interface interactions: phenomena, methods and limitations

et al. 1999

View full text Add to dashboard Cite

AbstractÐNanoindentation for measuring thin ®lm mechanical properties is probably the most popular yet ill-understood method due to its inherent complexities. As opposed to burst pressure or microtensile tests of lithographed structures, where relatively uniform stress ®elds may be generated, the indentation-induced stress gradients can produce unique challenges. Because of the test's simplicity and ability to mechanically probe the smallest of scales, it is becoming increasingly applied. Five possible stages of deformation are suggested from Hertzian elastic to ®lm delamination and double buckling. In particular metal ®lms on harder substrates are emphasized where it is shown that dislocation nucleation and arrest are only partially understood. Later stages of ®lm delamination are illustrated with Cu/SiO 2 /Si where it is shown that the true work of adhesion is 0.6 J/m 2 . Current limitations of indentation-induced delamination measures of toughness involve large scatter associated with sensitivity of the fracture radius to the contact radius ratio.

show abstract

“…But quantification of the rôle of n has so far been lacking. For polycrystalline metals, quantitative analyses [18,19] following Pugh [12] consider the stress state at a crack tip and the local conditions for spontaneous emission of dislocations. In metallic glasses, in contrast, plasticity is mediated by the shear bands.…”

Section: Introductionmentioning

confidence: 99%

Towards more uniform deformation in metallic glasses: The role of Poisson's ratio

Wei

Lei

Huo

et al. 2013

Materials Science and Engineering: A

View full text Add to dashboard Cite

a b s t r a c tWe develop a quantitative analysis of how the plastic deformation in a metallic glass is more uniform if its Poisson ratio n is higher. The plasticity of metallic glasses under ambient conditions is mediated by shear localized in thin bands, and can be characterized by experiments on the bending of thin plates. We extend the analysis by Conner et al. (Conner et al., J. Appl. Phys. 94 (2003), 904-911) of bands in bent plates to include the micromechanics of individual shear bands. Expressions are derived for the shearband spacing and the offset on each band. Both these quantities are predicted to decrease as n is increased. The predictions are tested against measurements on metallic glasses with a wide range of n.Good agreement is found, supporting the new model for the shear-band spacing, and pointing the way towards more diffuse deformation, and consequently improved plasticity and toughness, of metallic glasses as n increases toward the limiting value of 0.5. Crown

show abstract

Ductile versus brittle behaviour of crystals

Cited by 1,527 publications

References 20 publications

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Nanoindentation-induced defect–interface interactions: phenomena, methods and limitations

Towards more uniform deformation in metallic glasses: The role of Poisson's ratio

Contact Info

Product

Resources

About