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Microstructural effect on time-dependent plasticity of nanoporous gold.

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Title: Microstructural effect on time-dependent plasticity of nanoporous gold.
Authors: Kang, Na-Ri1, Gwak, Eun-Ji1, Jeon, Hansol1, Song, Eunji1, Kim, Ju-Young1 juyoung@unist.ac.kr
Source: International Journal of Plasticity. Oct2018, Vol. 109, p108-120. 13p.
Subjects: Microstructure, Grain size, Crystallography, Crystal grain boundaries, Material plasticity
Abstract: Annealed, prestrained, and ball-milled nanoporous gold (np-Au) samples were prepared. Since the microstructures of the precursor alloys, such as the crystallographic orientation and grain size, were mostly preserved during the dealloying process, prestrained np-Au is believed to have higher initial dislocation density, and ball-milled np-Au is believed to have higher densities of initial dislocation and grain boundary comparing to annealed np-Au. The time-dependent deformation behavior of np-Au samples with various microstructures was characterized with two parameters; creep strain exponent n and activation volume V ∗ using spherical nanoindentation creep tests. We found that primary mechanism of time-dependent plasticity for annealed and prestrained np-Au samples is dislocation slip and that for ball-milled np-Au sample is grain boundary sliding. In dislocation slip-dominant time-dependent deformation in np-Au, a higher initial dislocation density lowers n and V ∗ . In grain boundary sliding-dominant time-dependent deformation in np-Au, the values of n and V ∗ are similar to those for dislocation slip-dominant time-dependent deformation; however, the creep strain rate in quasi-steady-state is higher than that for dislocation slip-dominant time-dependent deformation. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Annealed, prestrained, and ball-milled nanoporous gold (np-Au) samples were prepared. Since the microstructures of the precursor alloys, such as the crystallographic orientation and grain size, were mostly preserved during the dealloying process, prestrained np-Au is believed to have higher initial dislocation density, and ball-milled np-Au is believed to have higher densities of initial dislocation and grain boundary comparing to annealed np-Au. The time-dependent deformation behavior of np-Au samples with various microstructures was characterized with two parameters; creep strain exponent n and activation volume V ∗ using spherical nanoindentation creep tests. We found that primary mechanism of time-dependent plasticity for annealed and prestrained np-Au samples is dislocation slip and that for ball-milled np-Au sample is grain boundary sliding. In dislocation slip-dominant time-dependent deformation in np-Au, a higher initial dislocation density lowers n and V ∗ . In grain boundary sliding-dominant time-dependent deformation in np-Au, the values of n and V ∗ are similar to those for dislocation slip-dominant time-dependent deformation; however, the creep strain rate in quasi-steady-state is higher than that for dislocation slip-dominant time-dependent deformation. [ABSTRACT FROM AUTHOR]
ISSN:07496419
DOI:10.1016/j.ijplas.2018.05.011