The Strength of Submicron-Sized Materials

Ngan, Ahw; Wo, P.C.; Zuo, L.; Li, H.; Afrin, N.

doi:10.1142/s0217979206040027

Cited by 4 publications

(2 citation statements)

References 21 publications

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“…This finding is interesting because it shows that the size effect can exist even without externally imposed strain gradients present in bending and indentation experiments. Several mechanisms have been proposed to explain the size effects in the micro-compression experiments [15,16]. We expect that dislocation dynamics (DD) simulations, when quantitatively compared with the experiments, will reveal the underlying mechanisms of this size dependence.…”

Section: Introductionmentioning

confidence: 96%

Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations

Greer

Weinberger

Cai

2008

Materials Science and Engineering: A

201

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We compare mechanical strength of f.c.c. gold and b.c.c. molybdenum single crystal pillars of sub-micrometer diameter in uniaxial compression tests. Both crystals show an increase of flow stress with decreasing diameter, but the change is more pronounced in Au than in Mo. The ratio between the observed maximum flow stress and the theoretical strength is much larger in Au pillars than in Mo pillars. Dislocation dynamics simulations also reveal different dislocation behavior in these two metals. While in a f.c.c. crystal a dislocation loop nucleated from the surface simply moves on its glide plane and exits the pillar, in a b.c.c. crystal it can generate multiple new dislocations due to the ease of screw dislocations to change slip planes. We postulate that this difference in dislocation behavior is the fundamental reason for the observed difference in the plastic deformation behavior of f.c.c. and b.c.c. pillars.

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Section: Introductionmentioning

confidence: 96%

Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations

Greer

Weinberger

Cai

2008

Materials Science and Engineering: A

201

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“…This may explain why the flow stress at 400 and 500 °C is also kept at high levels in our experiment. Additionally, the creep rate can be accelerated by dislocation glide, which has been observed in Ni 3 Al single-crystal pillars [79]. Another question is why Ni is more diffusive than Co, despite Co exhibits a slightly higher bulk diffusion coefficient than Ni in Al.…”

Section: Hybrid Diffusive-displacive Plasticitymentioning

confidence: 97%

Bridging room-temperature and high-temperature plasticity in decagonal Al–Ni–Co quasicrystals by micro-thermomechanical testing

Zou

Wheeler

Sologubenko

et al. 2016

Philosophical Magazine

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(2016) Bridging room-temperature and high-temperature plasticity in decagonal Al-Ni-Co quasicrystals by micro-thermomechanical testing, Philosophical Magazine, 96:32-34, 3356-3378, DOI: 10.1080/14786435.2016 Ever since quasicrystals were first discovered, they have been found to possess many unusual and useful properties. A long-standing problem, however, significantly impedes their practical usage: steadystate plastic deformation has only been found at high temperatures or under confining hydrostatic pressures. At low and intermediate temperatures, they are very brittle, suffer from low ductility and formability and, consequently, their deformation mechanisms are still not clear. Here, we systematically study the deformation behaviour of decagonal Al-Ni-Co quasicrystals using a micro-thermomechanical technique over a range of temperatures (25-500 °C), strain rates and sample sizes accompanying microstructural analysis. We demonstrate three temperature regimes for the quasicrystal plasticity: at room temperature, cracking controls deformation; at 100-300 °C, dislocation activities control the plastic deformation exhibiting serrated flows and a constant flow stress; at 400-500 °C, diffusion enhances the plasticity showing homogenous deformation. The micrometersized quasicrystals exhibit both high strengths of ~2.5-3.5 GPa and enhanced ductility of over 15% strains between 100 and 500 °C. This study improves understanding of quasicrystal plasticity in their lowand intermediate-temperature regimes, which was poorly understood before, and sheds light on their applications as small-sized structural materials.

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Ultra-strength materials

Zhu

2010

Progress in Materials Science

739

471

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Recent experiments on nanoscale materials, including nanowires, nanopillars, nanoparticles, nanolayers, and nanocrystals, have revealed a host of "ultra-strength" phenomena, defined by stresses in the material generally rising up to a significant fraction of the ideal strength-the highest achievable strength of a defect-free crystal. This article presents an overview of the strength-controlling deformation mechanisms and related mechanics models in ultra-strength nanoscale materials. The critical role of the activation volume is highlighted in understanding the deformation mechanisms, as well as the size, temperature, and strain rate dependence of ultra strength.

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The Strength of Submicron-Sized Materials

Cited by 4 publications

References 21 publications

Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations

Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations

Bridging room-temperature and high-temperature plasticity in decagonal Al–Ni–Co quasicrystals by micro-thermomechanical testing

Ultra-strength materials

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