Experimental Micromechanics Study of Lamellar TiA1

Abstract

A unique micro-scale full field deformation measurement technique called electron speckle photography is exploited to investigate the deformation mechanism of lamellar TiAl. We find the size of the specimen used and the area of strain measurement affect the mechanical properties thus obtained. The strain distribution inside a grain is highly heterogeneous. The grain boundary is much stiffer than the interior of the grain. We also observe several interesting phenomena of the material when a crack is present. Crack speed tends to slow down when the crack approaches a grain boundary. Within a grain the slowest propagation speed is when the lamellar layers are perpendicular to the crack. Crack may jump across a grain boundary and its propagation direction may be predicted by the strain concentration congregated near the grain boundary. By mapping the deformation field surrounding the crack tip, we can evaluate the mode mixity from the speckle results at different stages of crack propagation.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Feb 15, 2007
Accession Number
ADA464768

Entities

People

  • Fu-pen Chiang

Organizations

  • Stony Brook University

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Crack Propagation
  • Crack Tips
  • Electron Microscopes
  • Engineering
  • Failure Mode And Effect Analysis
  • Grain Boundaries
  • Materials
  • Materials Science
  • Mechanical Engineering
  • Mechanical Properties
  • Mechanics
  • Micromechanics
  • Photography
  • Resistance
  • Scanning Electron Microscopes
  • Stress Strain Relations
  • Stresses

Readers

  • Materials Science (Mechanical Engineering).
  • Powder metallurgy of Titanium alloys.

Technology Areas

  • Microelectronics