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Title: Phase transformation in tantalum under extreme laser deformation

The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [1]
  1. Univ. of California, San Diego, La Jolla, CA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. National Univ. of Cuyo, Mendoza (Argentina). Faculty of Exact and Natural Science; National Scientific and Technical Research Council (CONICET), Mendoza (Argentina)
Publication Date:
Report Number(s):
LLNL-JRNL-689346
Journal ID: ISSN 2045-2322
Grant/Contract Number:
AC52-07NA27344; 09-LR-06-118456-MEYM; PE-FG52-09NA-29043; NA0002080
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of California, San Diego, La Jolla, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Institutes of Health (NIH); Agouron Inst., Pasadena, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 36 MATERIALS SCIENCE
OSTI Identifier:
1252639
Alternate Identifier(s):
OSTI ID: 1259511; OSTI ID: 1462259; OSTI ID: 1462264

Lu, C. -H., Hahn, E. N., Remington, B. A., Maddox, B. R., Bringa, E. M., and Meyers, M. A.. Phase transformation in tantalum under extreme laser deformation. United States: N. p., Web. doi:10.1038/srep15064.
Lu, C. -H., Hahn, E. N., Remington, B. A., Maddox, B. R., Bringa, E. M., & Meyers, M. A.. Phase transformation in tantalum under extreme laser deformation. United States. doi:10.1038/srep15064.
Lu, C. -H., Hahn, E. N., Remington, B. A., Maddox, B. R., Bringa, E. M., and Meyers, M. A.. 2015. "Phase transformation in tantalum under extreme laser deformation". United States. doi:10.1038/srep15064. https://www.osti.gov/servlets/purl/1252639.
@article{osti_1252639,
title = {Phase transformation in tantalum under extreme laser deformation},
author = {Lu, C. -H. and Hahn, E. N. and Remington, B. A. and Maddox, B. R. and Bringa, E. M. and Meyers, M. A.},
abstractNote = {The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).},
doi = {10.1038/srep15064},
journal = {Scientific Reports},
number = ,
volume = 5,
place = {United States},
year = {2015},
month = {10}
}