An atomistic study of mechanical deformation of nanostructured Ni3Al synthesized by cluster compaction

Журкин, Е. Е.; Hou, Marc

doi:10.1016/j.jallcom.2006.08.183

Cited by 3 publications

(5 citation statements)

References 26 publications

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“…8 for the compacted and deposited samples at 0 K, showing a clear distinction between an elastic and a plastic regime. Similar results are found at nonzero temperatures, with a lower elastic limit, however, 45 and an elastic limit which is temperature dependent. In the elastic regime, Young's moduli are systematically lower than estimated for single crystals, but they are also decreasing with increasing temperature.…”

Section: A Deformation Regimessupporting

confidence: 81%

“…As shown in Ref. 45, in a perfect single crystal, the elastic strain increases linearly with the applied uniaxial stress over a large range of deformations and, in this regime, the slope of the strain-stress function depends on the direction in which the load is applied. For instance, the Young modulus at 0 K is estimated of 276 GPa in ͗111͘ directions and 100.4 GPa in ͗100͘ directions.…”

Section: A Deformation Regimesmentioning

confidence: 65%

“…Here, we focus on stress properties. We first recall previous work 45 about stress distributions in a perfect infinite L1 2 Ni 3 Al crystals which is used as a reference. The case of isolated nanoparticles is examined next, and the section ends with a discussion of cluster-assembled materials synthesized by cluster deposition and by compaction.…”

Section: Equilibrium Propertiesmentioning

confidence: 99%

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Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

2006

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Classical molecular dynamics with a semiempirical N-body potential is used to study the distribution of local stress in bimetallic Ni 3 Al nanoparticles and in cluster-assembled materials. The materials considered are synthesized with these particles by low-energy deposition at 0.5 eV per atom and by compaction with an external pressure of 2 GPa, thus featuring different nanostructures. Both are nanoporous, the lowest density being obtained by deposition. Their mechanical response to a uniaxial external load is then studied and deformation mechanisms are identified and are found to be similar in both nanostructures. In the core of isolated clusters, the partial pressures on the nickel and aluminium subsystems are found to differ by several GPa and, as a balance to surface tension, the hydrostatic core pressure is positive and depends on the cluster size. The surface stress is tensile and, because of structural disorder, the partial pressures distributions on Ni and Al at the surface are scattered. When nanostructured systems are formed, strong and highly inhomogeneous shear stress appears, the cluster cores may become tensile, and the interfacial areas remain mainly tensile as well. The partial pressure difference between Ni and Al is somewhat reduced. It is shown that the effect of temperature is to reduce this difference still further and to homogenize the spatial stress distribution. When subjected to a uniaxial stress, both materials display an elastic and a plastic regime. The elastic limit is the lowest for the most porous material and decreases with increasing temperature. Plastic deformation is dominated by both grain boundary sliding and by the enlargement of the open volumes, without evidence for the nucleation of cracks. These open volumes are found to facilitate dislocation activity which is evidenced in grains with sizes as small as two nanometers. This dislocation activity is found to result in the production of stacking faults as well as to the recovery of defects induced by the deposition or by the compaction.

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Section: A Deformation Regimessupporting

confidence: 81%

Section: A Deformation Regimesmentioning

confidence: 65%

Section: Equilibrium Propertiesmentioning

confidence: 99%

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Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

2006

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“…Comparing the results in ref. 23 with the present ones shows that, both in the case of the single crystal and of the n-wire, the effect of the n-wire surface is to decrease the Young modulus by almost a factor of 2 as compared with the bulk. The surface allows for limited plastic deformations in the n-wire, even at the lowest strains.…”

Section: Elastic Regimesupporting

confidence: 73%

“…The Young modulus obtained with the EAM potential is significantly smaller than with the TB potential while Poisson ratios are equal. Both estimates of E are smaller than estimated with the TB potential in an infinite single crystal in h100i directions, 23,24 also shown in Table 1 for comparison.…”

Section: Elastic Regimementioning

confidence: 81%

Mechanical properties of bimetallic crystalline and nanostructured nanowires

2008

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Nanowires are basic components of interconnects at the nanoscale level in electronic as well as in electromechanical devices. Presently, there is a fast growing interest in their synthesis as well as in their mechanical testing. Focused ion beams now allow machining pillars with diameters as small as a few tens of nanometres and nanoindenter systems allow measuring strains at the atomic scale and compressive stresses up to the 10 GPa range. Such pillars typically contain less than millions of atoms, which makes their modelling and the modelling of their mechanical properties at the atomic scale realistic. A few Molecular Dynamics studies are presently available, discussing deformation mechanisms in thin narrow crystalline nanowires, but the literature about nanoalloy wires and nanostructured wires, as they can be synthesized from clusters, is almost non-existent. In the latter, the dislocation activity may be inhibited, leading to specific mechanical properties. By means of large scale computations, we use Ni3A1 to discuss the mechanical properties of crystalline and nanostructured nanowires. We also compare wires to their bulk counterparts. Both isothermal and isoenergetic whereby mechanical work converts into heat in the system-deformation mechanisms are considered. The comparison between pair correlation functions, stress distributions, configuration analysis and strain stress relations capture most of the stress-induced evolution mechanisms of nanowires with different diameters and structures, including elastic properties, dislocation activity, grain rotation and boundary motion, local melting, superplasticity and fracture. A structural transition which may be martensitic is predicted for the first time at the nanoscale level, suggesting possible shape memory properties of nanoalloy nanowires.

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ATOMISTIC SIMULATION OF THE MECHANICAL BEHAVIOR OF Ni₃Al NANOWIRES

Cheng

Wang

et al. 2010

Mod. Phys. Lett. B

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Simulations have been carried out on [001]-oriented Ni 3 Al nanowires with square cross-section with the purpose to investigate the mechanism of failure under tensile and compressive strain. Simulation results show that the elastic limit of the nanowire is up to about 15% strain with the yield stress of 5.99–6.48 GPa under tensile strain. Under the elastic stage, the deformation is carried mainly through the uniform elongation of the bonds between atoms. With more tensile strain, the slips in the {111} planes occur to accommodate the applied strain at room temperature under tensile strain. And the nanowires accommodate the compressive strain by forming the twins within the nanowires.

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An atomistic study of mechanical deformation of nanostructured Ni3Al synthesized by cluster compaction

Cited by 3 publications

References 26 publications

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

Mechanical properties of bimetallic crystalline and nanostructured nanowires

ATOMISTIC SIMULATION OF THE MECHANICAL BEHAVIOR OF Ni₃Al NANOWIRES

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An atomistic study of mechanical deformation of nanostructured Ni3Al synthesized by cluster compaction

Cited by 3 publications

References 26 publications

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

Stress distribution and mechanical properties of free and assembledNi3Alnanoclusters

Mechanical properties of bimetallic crystalline and nanostructured nanowires

ATOMISTIC SIMULATION OF THE MECHANICAL BEHAVIOR OF Ni3Al NANOWIRES

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Product

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ATOMISTIC SIMULATION OF THE MECHANICAL BEHAVIOR OF Ni₃Al NANOWIRES