skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

This content will become publicly available on November 15, 2020

Title: Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state

Abstract

Ductile rupture or tearing usually involves structural degradation from the nucleation and growth of voids and their coalescence into cracks. Although some materials contain preexisting pores, the first step in failure is often the formation of voids. Because this step can govern both the failure strain and the fracture mechanism, it is critical to understand the mechanisms of void nucleation and the enabling microstructural configurations which give rise to nucleation. To understand the role of dislocations during void nucleation, the present study presents ex-situ cross-sectional observations of interrupted deformation experiments revealing incipient, subsurface voids in a copper material containing copper oxide inclusions. The local microstructural state was evaluated using electron backscatter diffraction (EBSD), electron channeling contrast (ECC), transmission electron microscopy (TEM), and transmission kikuchi diffraction (TKD). Surprisingly, before substantial growth and coalescence had occurred, the deformation process had resulted in the nucleation of a high density of nanoscale (≈50 μm) voids in the deeply deformed neck region where strains were on the order of 1.5. Such a proliferation of nucleation sites immediately suggests that the rupture process is limited by void growth, not nucleation. With regard to void growth, analysis of more than 20 microscale voids suggests that dislocation boundariesmore » facilitate the growth process. The present observations call into question prior assumptions on the role of dislocation pile-ups and provide new context for the formulation of revised ductile rupture models. While the focus of this study is on damage accumulation in a highly ductile metal containing small, well-dispersed particles, these results are also applicable to understanding void nucleation in engineering alloys.« less

Authors:
 [1];  [2];  [2]; ORCiD logo [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1574704
Report Number(s):
SAND-2019-8768J
Journal ID: ISSN 1359-6454; 677887
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Name: Acta Materialia; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
Void growth; Dislocation cell; Vacancy condensation; Void nucleation; Ductile failure

Citation Formats

Noell, Philip J., Sabisch, Julian E. C., Medlin, Douglas L., and Boyce, Brad L. Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state. United States: N. p., 2019. Web. doi:10.1016/j.actamat.2019.11.022.
Noell, Philip J., Sabisch, Julian E. C., Medlin, Douglas L., & Boyce, Brad L. Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state. United States. doi:10.1016/j.actamat.2019.11.022.
Noell, Philip J., Sabisch, Julian E. C., Medlin, Douglas L., and Boyce, Brad L. Fri . "Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state". United States. doi:10.1016/j.actamat.2019.11.022.
@article{osti_1574704,
title = {Nanoscale conditions for ductile void nucleation in copper: vacancy condensation and the growth-limited microstructural state},
author = {Noell, Philip J. and Sabisch, Julian E. C. and Medlin, Douglas L. and Boyce, Brad L.},
abstractNote = {Ductile rupture or tearing usually involves structural degradation from the nucleation and growth of voids and their coalescence into cracks. Although some materials contain preexisting pores, the first step in failure is often the formation of voids. Because this step can govern both the failure strain and the fracture mechanism, it is critical to understand the mechanisms of void nucleation and the enabling microstructural configurations which give rise to nucleation. To understand the role of dislocations during void nucleation, the present study presents ex-situ cross-sectional observations of interrupted deformation experiments revealing incipient, subsurface voids in a copper material containing copper oxide inclusions. The local microstructural state was evaluated using electron backscatter diffraction (EBSD), electron channeling contrast (ECC), transmission electron microscopy (TEM), and transmission kikuchi diffraction (TKD). Surprisingly, before substantial growth and coalescence had occurred, the deformation process had resulted in the nucleation of a high density of nanoscale (≈50 μm) voids in the deeply deformed neck region where strains were on the order of 1.5. Such a proliferation of nucleation sites immediately suggests that the rupture process is limited by void growth, not nucleation. With regard to void growth, analysis of more than 20 microscale voids suggests that dislocation boundaries facilitate the growth process. The present observations call into question prior assumptions on the role of dislocation pile-ups and provide new context for the formulation of revised ductile rupture models. While the focus of this study is on damage accumulation in a highly ductile metal containing small, well-dispersed particles, these results are also applicable to understanding void nucleation in engineering alloys.},
doi = {10.1016/j.actamat.2019.11.022},
journal = {Acta Materialia},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {11}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on November 15, 2020
Publisher's Version of Record

Save / Share: