YOU CAN GIVE NEW INSIGHTS BY USE OF A TEM IN THE STUDY OF DISLOCATIONS AND FATIGUE CRACKING

transmission electron microscopy (TEM) in dislocation and fatigue cracking studies shows that structures formed by dislocations in fatiguing materials may contribute indirectly to crack propagation. Work is reported which attempts to characterize this fatigue-induced dislocation structure in pure copper to ascertain what is unique about it and how it might contribute to fatigue cracking. Major anomalies of fatigue behavior can be explained by the distinct dislocation cell structures associated with the fatigue crack tip. A Hitache HU II 100 kV microscope operating at its maximum output was used in the studies. The scheme employed to obtain specimens for electron microscopy viewing is outlined. It was found that cyclic stressing of fatigue creates a dense, complex dislocation cell structure in the fatigue crack tip region that supersedes surrounding material. They very likely contain small zones of high hardness or "susceptibility zones" which are highly vulnerable to brittle fracture. Cracks formed within these zones can link up as fatiguing progresses, with the rusultant formation of a macroscopic fatigue crack.

• Corporate Authors:

  Dun Donnelley Publishing Corporation

  222 South Riverside Plaza
  Chicago, IL  United States  60606
• Authors:
  • Purcell, A H
• Publication Date: 1977-4

Media Info

• Features: Figures; Photos; References;
• Pagination: p. 81-84
• Serial:
  • Industrial Research
  • Volume: 19
  • Issue Number: 4
  • Publisher: Dun Donnelley Publishing Corporation

Subject/Index Terms

• TRT Terms: Cellular structures; Copper; Dislocations; Electron microscopes; Fatigue (Mechanics); Fracture mechanics
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00157758
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 13 1977 12:00AM