Nanotwinned alloys under high pressure
Journal Article
·
· Acta Materialia
- Stanford Univ., CA (United States)
- Nanyang Technological Univ. (Singapore); Agency for Science, Technology and Research (A*STAR) (Singapore)
- Stanford Univ., CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Agency for Science, Technology and Research (A*STAR) (Singapore)
- Univ. of Chicago, IL (United States)
- Univ. of Southern California, Los Angeles, CA (United States)
Nanotwinned alloys are of interest due to their high strength and ductility, but twin boundaries may not be stable under shear. Computational studies indicate that high hydrostatic pressure may suppress detwinning mechanisms. Here, in this study, we investigate the microstructural changes of nanotwinned-nanocrystalline copper-nickel and Inconel 725 alloys under quasi-hydrostatic pressures up to 50 gigapascals (GPa). The alloys are compressed in a diamond anvil cell. In-situ x-ray diffraction (XRD) and ex-situ transmission electron microscopy (TEM) were employed to monitor microstructural changes. Twin boundary deformation and grain growth occur at 11.4 GPa quasi-hydrostatic pressure in the copper-nickel alloy. Molecular dynamics (MD) simulations reveal that hydrostatic pressure causes elevated local shear stress at grain boundaries, which leads to atomic rearrangements. A superposition of hydrostatic and deviatoric pressures lead to partial dislocation mediated twin boundary migration. In contrast, the Inconel 725 alloy showed stable twin and grain boundaries up to a quasi-hydrostatic pressure of 12.7 GPa. Texture, high solid solution strengthening, and low stacking fault energy are hypothesized to the enhanced microstructural stability in Inconel 725.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- A*STAR Merit Award Fellowship; National Science Foundation (NSF); US Army Research Office (ARO); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
- Grant/Contract Number:
- AC02-06CH11357; AC52-07NA27344; FG02-94ER14466
- OSTI ID:
- 2516796
- Report Number(s):
- LLNL--JRNL-863235; 1096221
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Vol. 285; ISSN 1359-6454
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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