G. Sainath

Size dependent deformation behaviour and dislocation mechanisms in 〈1 0 0〉 Cu nanowires

Abstract Molecular dynamics simulations have been performed to understand the size-dependent tensile deformation behaviour of 〈1 0 0〉 Cu nanowires at 10 K. The influence of nanowire size has been examined by varying square cross-section width (d) from 0.723 to 43.38 nm using constant length of 21.69 nm. The results indicated that the yielding in all the nanowires occurs through nucleation of partial dislocations. Following yielding, the plastic deformation in small size nanowires occurs mainly by slip of partial dislocations at all strains, while in large size nanowires, slip of extended dislocations has been observed at high strains in addition to slip of partial dislocations. Further, the variations in dislocation density indicated that the nanowires with d > 3.615 nm exhibit dislocation exhaustion at small strains followed by dislocation starvation at high strains. On the other hand, small size nanowires with d < 3.615 nm displayed mainly dislocation starvation at all strains. The average length of dislocations has been found to be same and nearly constant in all the nanowires. Both the Young’s modulus and yield strength exhibited a rapid decrease at small size nanowires followed by gradual decrease to saturation at larger size. The observed linear increase in ductility with size has been correlated with the pre- and post-necking deformation. Finally, dislocation–dislocation interactions leading to the formation of various dislocation locks, the dislocation–stacking fault interactions resulting in the annihilation of stacking faults and the size dependence of dislocation–surface interactions have been discussed.

Effects of temperature and strain rate on tensile stress–strain and workhardening behaviour of P92 ferritic steel

Abstract Detailed analysis on true stress σ–true plastic strain ϵ data indicated that the tensile flow and workhardening behaviour of P92 ferritic steel can be described most accurately by the combination of Ludwigson and Hollomon relations at strain rates ranging from 3·16×10−5 to 1·26×10−3 s−1 over the temperature range of 300–923 K. At room and intermediate temperatures, the Ludwigson equation follows the σ–ϵ data closely, whereas at high temperatures, the Ludwigson equation reduces to the Hollomon relation. The variations in σ–ϵ, workhardening parameters and θ–σ with temperature exhibited three distinct temperature regimes. At intermediate temperatures, anomalous variations in σ–ϵ, workhardening parameters and θ–σ with respect to temperature and strain rate have been observed. At high temperatures, the dominance of recovery is reflected in the rapid decrease in flow stress and workhardening parameters associated with Ludwigson/Hollomon relations with increasing temperature and decreasing strain rate.

Effect of orientation and mode of loading on deformation behaviour of Cu nanowires

Molecular dynamics simulations have been performed to understand the variations in deformation mechanisms of Cu nanowires as a function of orientation and loading mode (tension or compression). Cu nanowires of different crystallographic orientations distributed uniformly on the standard stereographic triangle have been considered under tensile and compressive loading. The simulation results indicate that under compressive loading, the orientations close to

Molecular dynamics simulation studies on the size dependent tensile deformation and fracture behaviour of body centred cubic iron nanowires

corner deform by twinning mechanism, while the remaining orientations deform by dislocation slip. On the other hand, all the nanowires deform by twinning mechanism under tensile loading. Further, the orientations close to

Applicability of Voce equation for tensile flow and work hardening behaviour of P92 ferritic steel

and

Molecular dynamics simulation studies on the influence of aspect ratio on tensile deformation and failure behaviour of 〈1 0 0〉 copper nanowires

corner exhibit tension-compression asymmetry in deformation mechanisms. In addition to deformation mechanisms, Cu nanowires also display tension-compression asymmetry in yield stress. The orientations close to