Al–Pd–Mn icosahedral quasicrystal: deformation mechanisms in the brittle domain

Texier, M.; Joulain, Anne; Bonneville, J.; Thilly, L.; Rabier, J.

doi:10.1080/14786430601047707

Cited by 12 publications

(7 citation statements)

References 40 publications

(47 reference statements)

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“…It has been a long-standing question concerning the deformation mechanism in quasicrystals at room temperature. Despite several investigators have sought to explore the plastic deformation of quasicrystals at or near room temperature using indentation or by confining gas or solid pressures 19 20 21 22 , so far there has been no common conclusion: the explanations include shear banding similar to metallic glasses 23 , phase transformation 24 25 , grain-boundary glide 21 , pure dislocation climb 22 , dislocation climb dominant 26 and crystallization 27 . Therefore, one has to conclude that the plastic deformation of quasicrystals under a wide range of temperatures and pressures has been poorly understood—much in contrast to crystalline and amorphous solids.…”

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confidence: 99%

Superior room-temperature ductility of typically brittle quasicrystals at small sizes

et al. 2016

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The discovery of quasicrystals three decades ago unveiled a class of matter that exhibits long-range order but lacks translational periodicity. Owing to their unique structures, quasicrystals possess many unusual properties. However, a well-known bottleneck that impedes their widespread application is their intrinsic brittleness: plastic deformation has been found to only be possible at high temperatures or under hydrostatic pressures, and their deformation mechanism at low temperatures is still unclear. Here, we report that typically brittle quasicrystals can exhibit remarkable ductility of over 50% strains and high strengths of ∼4.5 GPa at room temperature and sub-micrometer scales. In contrast to the generally accepted dominant deformation mechanism in quasicrystals—dislocation climb, our observation suggests that dislocation glide may govern plasticity under high-stress and low-temperature conditions. The ability to plastically deform quasicrystals at room temperature should lead to an improved understanding of their deformation mechanism and application in small-scale devices.

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confidence: 99%

Superior room-temperature ductility of typically brittle quasicrystals at small sizes

et al. 2016

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“…Plastic deformation in the brittle domain has only been reported for compression or shear deformation under confining pressure. 12 The dislocations seem to move by climb. No evidence of dislocation activity is detected in areas where fracture occurs.…”

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confidence: 96%

Comment on “Cleaved surface ofi-AlPdMnquasicrystals: Influence of the local temperature elevation at the crack tip on the fracture surface roughness”

Rösch

Trebin

2008

Phys. Rev. B

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Quasicrystals are intermetallic compounds with long-range quasiperiodic translational order, composed of atomic clusters, which can be interpreted as basic geometric building blocks. It is a persistent discussion whether these clusters also represent physical entities. Cleavage planes of fractured icosahedral AlPdMn as well as sputtered surfaces annealed up to about 900 K are rough with clusterlike protrusions. Fivefold surfaces annealed at higher temperatures exhibit flat terraces. Thus, obviously, the clusters cannot be termed supermolecules. However, experiments and numerical simulations indicate that fracture is influenced by the clusters. Thus, they determine physical properties. In a recent paper, Ponson et al. ͓Phys. Rev. B 74, 184205 ͑2006͔͒ investigated experimental fracture surfaces of AlPdMn and questioned the signature of the clusters. In this comment, we study the self-affinity of cleavage planes obtained by molecular-dynamics simulations. We conclude that the findings of Ponson et al. are not excluding a physical role of the clusters in quasicrystals.One method to analyze the roughness of fracture surfaces is to calculate the height-height correlation functions. These reveal scaling properties ͑see Ref. 1 for a review paper͒ with a "universal" roughness exponent of about 0.8 for a wide range of materials. However, up to now, no theoretical model is able to satisfactorily capture this self-affinity. Thus, it is hard to interpret microscopic properties of the investigated structures starting from the scaling behavior. It might even not be possible to distinguish a fractured from a sputtered surface, as the roughness exponents of both surfaces can lie in the same range. 2,3 Although the scaling behavior of fracture surfaces seems to be universal, the range of length scales in which it is valid may strongly vary for different materials. It has been argued that the corresponding cut-off length is related to the size of the process zone R c . 4 Inside this region, linear elastic predictions do not fit the real deformation field. Such a nonlinear and dissipative zone always exists, as atomic bonds break at the crack tip. The behavior on and below this scale determines whether, how, and where a crack travels. R c should therefore be related to the microstructure. In the following, we investigate the role and interpretation of for fracture surfaces of icosahedral quasicrystals. The roughness of i-AlPdMn fracture surfaces was analyzed in a recent paper by Ponson et al. 5 They found scaling properties which resemble those of various disordered materials. The height-height correlation function reveals a selfaffine behavior from the atomic scale up to Ϸ 2 nm. The corresponding Hurst exponent H is found to be about 0.72 ͑see Fig. 2 of Ref. 5͒. The authors pointed out that the selfaffine region includes the radius of the clusters r c Ϸ 0.5 nm, which are inherent in the structure. It is stated that the morphology of the fracture surfaces therefore does not reflect the cluster distribution. Thus, the influence of th...

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“…So far, no agreed conclusion has been reached, and some explanations are: grain-boundary glide rather than a dislocation mechanism [25], pure dislocation climb [15], dominant climb with possible glide [16], phase transformations [26], the nucleation and propagation of shear bands similar to metallic glasses [27]. Still, the plasticity of quasicrystals was poorly explored in a wide range of temperature and pressure -much in contrast to that of crystalline and amorphous solids.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous studies explored the low-temperature plastic behaviour of QCs by either indentation [25] or gas/solid hydrostatic pressures [15,16]. So far, no agreed conclusion has been reached, and some explanations are: grain-boundary glide rather than a dislocation mechanism [25], pure dislocation climb [15], dominant climb with possible glide [16], phase transformations [26], the nucleation and propagation of shear bands similar to metallic glasses [27].…”

Section: Introductionmentioning

confidence: 99%

“…Despite their interesting structures and useful properties, however, very few QCs have been converted into practical products. A well-known drawback that hinders their application is that they are intrinsically brittle: plastic deformation is only possible at high temperatures (above ~75% of their melting temperatures, T m ) [12][13][14] or under confining hydrostatic pressures [15,16]. Deformation at low and intermediate temperatures generally results in a catastrophic failure [17], rendering them very difficult to further process and often unsuitable for use.…”

Section: Introductionmentioning

confidence: 99%

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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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Al–Pd–Mn icosahedral quasicrystal: deformation mechanisms in the brittle domain

Cited by 12 publications

References 40 publications

Superior room-temperature ductility of typically brittle quasicrystals at small sizes

Superior room-temperature ductility of typically brittle quasicrystals at small sizes

Comment on “Cleaved surface ofi-AlPdMnquasicrystals: Influence of the local temperature elevation at the crack tip on the fracture surface roughness”

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

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