Crystallographic effects on the fatigue fracture of copper- sapphire interfaces

Pedro Peralta, U. Ramamurty, S. Suresh, G. H. Campbell, W. E. King, T. E. Mitchell

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Interfacial fatigue cracks were propagated in copper-sapphire bicrystals with the boundary perpendicular to the load axis and (1 10)Cu║║(1010)A12O3— [001]Cu║║ [0001 ] A12O3to study the effect of crystallography in the fracture process. Cylindrical samples with a circumferential notch were loaded in compression- compression and compact tension specimens in tension-tension. Three interfacial cracks in the cylindrical sample nucleated simultaneously at sites corresponding to the maximum slip length, under local single slip conditions, for three of the four slip vectors expected for the (110) loading axis in the copper crystal. These cracks arrested with continued cycling, while two new cracks nucleated at 0° and 180° from [110]Cuwhich also self-arrested. Then another crack started at 90° from [110]Cuand grew with an inclined front. Striations could be observed on the copper fracture surfaces; however, they did not coincide macroscopically with traces of (111) slip planes. Large areas were also relatively free of features. Elastic analysis of the anisotropic near-tip stress fields for the interfacial crack revealed that the dominant crack growth direction had the highest energy release rate, whereas the second crack direction had the minimum mode II mix. A model to account for the noncrystallographic striations is proposed.

Original languageEnglish (US)
Pages (from-to)2109-2129
Number of pages21
JournalPhilosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
Volume80
Issue number9
DOIs
StatePublished - Sep 2000

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Science(all)
  • Condensed Matter Physics
  • Physics and Astronomy (miscellaneous)
  • Metals and Alloys

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