Atomic Simulations on the Grain Subdivision of a Crystalline Metal

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The relationship between grain subdivision mechanisms of a crystalline metal and the strain gradient under severe plastic deformation is studied by using molecular dynamics simulations in quasi two dimensions. Two problems are simulated for single crystal models: (a) uniaxial tensile and compressive deformation and (b) localized shear deformation. In the case of uniaxial deformation, a large number of dislocation pairs with opposite Burgers vectors are generated under deformation, but most dislocations are vanished due to pair annihilation under relaxation. Therefore, no dislocation boundary can be formed. On the other hand, in case of localized shear deformation with large strain gradient, dislocation boundaries are formed between undeformed and deformed regions. These dislocations can be regarded as geometrically necessary dislocations. Consequently, the importance of the strain gradient to make grain boundaries under plastic deformation can be confirmed by atomic simulations.

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Periodical:

Materials Science Forum (Volumes 561-565)

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Edited by:

Young Won Chang, Nack J. Kim and Chong Soo Lee

Pages:

1983-1986

Citation:

T. Shimokawa et al., "Atomic Simulations on the Grain Subdivision of a Crystalline Metal", Materials Science Forum, Vols. 561-565, pp. 1983-1986, 2007

Online since:

October 2007

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$38.00

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0 0. 2 0. 4 0. 6 0. 8 1. 0 1. 2 1. 4 proportion of defects γ time [ns] proportion of defects all defects defects in grain boundaries fgb allf 1st process 2nd process 3rd process.

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06 BA A AB B Fig. 4 Proportion of defects Fig. 5 The fall vs the number of deformation processes.