Deformation defects in nanocrystalline nickel

Wu, Xiaolei; Ma, E.; Zhu, Yuntian

doi:10.1007/s10853-006-1229-7

Cited by 31 publications

(19 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This could sometimes lead to serious problems because it is known that grain sizes affect the deformation mechanisms [24,37,57,59,171,185]. For example, it was observed by MD simulations that nc Al, Cu and Ni rarely deform by twinning [10], which contradicts the experimental observations [2,6,23,[33][34][35]66,68,77,[186][187][188][189]. This controversy was later found caused by the grain size effect, i.e.…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

“…However, in nc fcc metals, multiple twins often form, which show no obvious plate-like morphology (see Fig. 5b) [34,42,56,[65][66][67][68][69][70]. Under such circumstances, HREM is needed to identify and study the deformation twins.…”

Section: Basics Of Deformation Twinning In Fcc Metalsmentioning

confidence: 99%

“…The samples used for experimental studies have been prepared by mechanical attrition [65], physical vapor deposition [6], high-pressure torsion [8], surface mechanical attrition [223], electro-deposition [35,40,41,68], inert gas condensation [15], etc. Each of these methods may have its own intrinsic issue such as impurities, unclean grain boundaries, and non-equilibrium grain boundaries.…”

Section: Experimental Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Deformation twinning in nanocrystalline materials

Zhu

Liao

2012

Progress in Materials Science

1,170

447

View full text Add to dashboard Cite

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Section: Basics Of Deformation Twinning In Fcc Metalsmentioning

confidence: 99%

Section: Experimental Observationsmentioning

confidence: 99%

See 1 more Smart Citation

Deformation twinning in nanocrystalline materials

Zhu

Liao

2012

Progress in Materials Science

1,170

447

View full text Add to dashboard Cite

“…Among such metals, copper, nickel and aluminum have been the most extensively studied [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. For those fcc metals, a grain size as small as 10 nm can be produced by various techniques.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion

et al. 2011

View full text Add to dashboard Cite

Wei, Q.; Pan, Z. L.; Wu, X. L.; Schuster, B. E.; Kecdkes, L. J.; and Valiev, R. Z., "Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion" (2011 AbstractFully dense, nanocrystalline tantalum (average grain size as small as $40 nm) has been processed for the first time by high-pressure torsion. High-resolution transmission electron microscopy reveals non-equilibrium grain boundaries and grains decorated with high-density dislocations. Microhardness measurements and instrumented nanoindentation experiments indicate that the mechanical property is quite uniform except for the central area of the disks. Nanoindentation experiments at different strain rates suggest that the strain rate sensitivity of nanocrystalline tantalum is increased compared to the coarse-and ultrafine-grained counterparts and is accompanied by an activation energy of the order of a few $b 3 (b is the magnitude of the dislocation Burgers vector), implying a shift in the plastic deformation mechanism from the screw dislocation dominated regime. We thus infer the plastic deformation mechanisms of nanocrystalline body-centered cubic (bcc) and face-centered cubic metals converge. To examine the stress-strain behavior, we have used microcompression to measure the compressive stress-strain curves on microscale pillars fabricated by focused ion beam technique. Yield strength as high as 1.6 GPa has been observed. High-strain rate behavior has been investigated using a miniature Kolsky bar system. We have found that at high-strain rates the nanocrystalline tantalum specimens exhibit adiabatic shear banding, a dynamic plastic deformation mode common to many ultrafine-grained and all nanocrystalline bcc metals.

show abstract

“…It is generally thought that FCC metals with grain size 50-100 nm deform predominantly via the slip of lattice dislocations, and for grains larger than 100nm they deform exclusively through this mechanism [ 10 ]. Various works have shown that in nanostructured materials (grain size < 50 nm) alternative deformation mechanisms involving deformation twins [11,12,13], and stacking faults (SFs) [14,15] can occur. In some cases these types of defects have even been observed in grains with size up to 100 nm [12], but it is not evident that they make a significant contribution to deformation in these SPD processed materials.…”

Section: Introductionmentioning

confidence: 99%

Predicting grain refinement by cold severe plastic deformation in alloys using volume averaged dislocation generation

et al. 2009

View full text Add to dashboard Cite

The grain refinement during severe plastic deformation (SPD) is predicted using volume averaged amount of dislocations generated. The model incorporates a new expansion of a model for hardening in the parabolic hardening regime, in which the work hardening depends on the effective dislocation free path related to the presence of non shearable particles and solute-solute nearest neighbour interactions.These two mechanisms give rise to dislocation multiplication in the form of generation of geometrically necessary dislocations and dislocations induced by local bond energies. The model predicts the volume averaged amount of dislocations generated and considers that they distribute to create cell walls and move to existing cell walls/grain boundaries where they increase in the grain boundary misorientation. The model predicts grain sizes of Al alloys subjected to SPD over 2 orders of magnitude. The model correctly predicts the considerable influence of Mg content and content of nonshearable particles on the grain refinement during SPD.

show abstract

Deformation defects in nanocrystalline nickel

Cited by 31 publications

References 40 publications

Deformation twinning in nanocrystalline materials

Deformation twinning in nanocrystalline materials

Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion

Predicting grain refinement by cold severe plastic deformation in alloys using volume averaged dislocation generation

Contact Info

Product

Resources

About