Title: Strength and deformation of shocked diamond single crystals: Orientation dependence

Abstract

Understanding and quantifying the strength or elastic limit of diamond single crystals is of considerable scientific and technological importance, and has been a subject of long standing theoretical and experimental interest. To examine the effect of crystalline anisotropy on strength and deformation of shocked diamond single crystals, plate impact experiments were conducted to measure wave profiles at various elastic impact stresses up to ~120 GPa along [110] and [111] crystal orientations. Using laser interferometry, particle velocity histories and shock velocities in the diamond samples were measured and were compared with similar measurements published previously for shock compression along the [100] direction. Wave profiles for all three orientations showed large elastic wave amplitudes followed by time-dependent inelastic deformation. From the measured wave profiles, the elastic limits were determined under well characterized uniaxial strain loading conditions. The measured elastic wave amplitudes for the [110] and [111] orientations were lower for higher elastic impact stress (stress attained for an elastic diamond response), consistent with the result reported previously for [100] diamond. The maximum resolved shear stress (MRSS) on the {111}(110) slip systems was determined for each orientation, revealing significant orientation dependence. The MRSS values for the [100] and [110] orientations (~33 GPa) aremore » 25%–30% of theoretical estimates; the MRSS value for the [111] orientation is significantly lower (~23 GPa). Our results demonstrate that the MRSS depends strongly on the stress component normal to the {111} planes or the resolved normal stress (RNS), suggesting that the RNS plays a key role in inhibiting the onset of inelastic deformation. Lower elastic wave amplitudes at higher peak stress and the effect of the RNS are inconsistent with typical dislocation slip mechanisms of inelastic deformation, suggesting instead an inelastic response characteristic of shocked brittle solids. The present results show that the elastic limit (or material strength) of diamond single crystals cannot be described using traditional isotropic approaches, and typical plasticity models cannot be used to describe the inelastic deformation of diamond. Analysis of the measured wave profiles beyond the elastic limit, including characterization of the peak state, requires numerical simulations that incorporate a time-dependent, anisotropic, inelastic deformation response. Development of such a material description for diamond is an important need.« less

Authors:

Lang, John Michael Jr.  ^[1];

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Winey, J. M. ^[2]; Gupta, Y. M. ^[2]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Washington State Univ., Pullman, WA (United States)
2. Washington State Univ., Pullman, WA (United States)

Publication Date:

Thu Mar 01 00:00:00 EST 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Washington State Univ., Pullman, WA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1430007

Alternate Identifier(s):

OSTI ID: 1426837; OSTI ID: 1476638

Report Number(s):

LA-UR-17-28218
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1802489

Grant/Contract Number:  

AC52-06NA25396; NA0000970; NA0002007

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 97; Journal Issue: 10; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Compressive strength; Crystal phenomena; Elastic deformation; Elasticity; Material failure