Young's modulus, poisson's ratio, and nanoscale deformation fields of MEMS materials

Ioannis Chasiotis, S. W. Cho, T. A. Friedmann, J. P. Sullivan

Research output: Contribution to journalConference articlepeer-review

Abstract

The mechanical properties of hydrogen-free tetrahedral amorphous diamond-like carbon have been investigated in connection with its elastic and failure properties. Micro-tension specimens of gage thickness of 1.2-1.8 μm and widths of 10 μm or 50 μm have been fabricated by the Sandia National Laboratories (SNL). The mechanical characterization has been conducted via in situ AFM measurements and Digital Image Correlation (DIC) data strain analysis and the local deformation fields of (a) uniform and (b) internally notched tension specimens with acute notches (K=27) have been experimentally obtained. Young's modulus and Poisson's ratio were measured for the first time directly from such small specimens and averaged 750 GPa and v=0.16 respectively, while the tensile strength was found to be very consistent averaging 7.1 GPa. Stressed material domains with smaller dimensions in the vicinity of micronotches exhibited even higher failure strengths reaching 11.5 GPa with limited data scatter. AFM images of in situ tested specimens have indicated sp 3 to sp 2 phase transformations on the film surface that was subject to ultra-high tensile stresses (>6 GPa). This is the first time these phase transformations are observed during tensile tests of brittle materials.

Original languageEnglish (US)
Pages (from-to)461-466
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume795
StatePublished - 2003
Externally publishedYes
EventThin Films - Stresses and Mechanical Properties X - Boston, MA., United States
Duration: Dec 1 2003Dec 5 2003

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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