Mechanisms of Dynamic Deformation and Dynamic Failure in Aluminum Nitride

Abstract

Uniaxial quasi-static, uniaxial dynamic and confined dynamic compression experiments have been performed to characterize the failure and deformation mechanisms of a sintered polycrystalline aluminum nitride using a servohydraulic machine and a modified Kolsky bar. Scanning electron microscopy and transmission electron microscopy (TEM) are used to identify the fracture and deformation mechanisms under high rate and high pressure loading conditions. These results show that the fracture mechanisms are strong functions of confining stress and strain rate, with transgranular fracture becoming more common at high strain rates. Dynamic fracture mechanics and micromechanical models are used to analyze the observed fracture mechanisms. TEM characterization of fragments from the confined dynamic experiments shows that at higher pressures dislocation motion becomes a common dominant deformation mechanism in AlN. Prismatic slip is dominant, and pronounced microcrack- dislocation interactions are observed, suggesting that the dislocation plasticity affects the macroscopic fracture behavior in this material under high confining stresses.

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 2012
Accession Number
ADA568595

Entities

People

  • C. Q. Chen
  • Guangli Hu
  • J. W. Mccauley
  • K. T. Ramesh

Organizations

  • Johns Hopkins University

Tags

Communities of Interest

  • Air Platforms
  • Weapons Technologies

DTIC Thesaurus Topics

  • Aluminum Nitrides
  • Crystal Structure
  • Electron Microscopy
  • Failure Mode And Effect Analysis
  • Fracture (Mechanics)
  • High Pressure
  • Hydrostatic Pressure
  • Materials
  • Mechanical Properties
  • Mechanical Working
  • Mechanics
  • Microscopy
  • Plastic Properties
  • Polycrystals
  • Scanning Electron Microscopy
  • Strain Rate
  • Transmission Electron Microscopy

Readers

  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.
  • Mechanical Engineering/Mechanics of Materials.

Technology Areas

  • Microelectronics