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Subcritical Crack Growth in Y‐TZP and Al 2 O 3 ‐Toughened Y‐TZP
Author(s) -
Knechtel Mathias C.,
Garcia Daniel E.,
Rödel Jürgen,
Claussen Nils
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb04001.x
Subject(s) - materials science , stress intensity factor , composite material , electromagnetic shielding , stress (linguistics) , stress field , tension (geology) , shielding effect , optical microscope , fracture mechanics , fracture (geology) , crack closure , cracking , scanning electron microscope , ultimate tensile strength , structural engineering , linguistics , philosophy , finite element method , engineering
Crack velocity curves for Y‐TZP and Al 2 O 3 ‐toughened Y‐TZP were determined for long cracks in compact tension specimens with an in situ fracture device on the stage of an optical microscope. Indications for a crack velocity threshold were found for both materials. Above this threshold, at 2.6 MPa·m 1/2 for Y‐TZP and 3.6 MPa·m 1/2 for Al 2 O 3 ‐toughened Y‐TZP, chemically assisted subcritical crack growth occurs over an extended regime of applied stress intensity factors of width 2.1–2.8 MPa·m 1/2 . It is recognized that the dependence of the shielding term on the crack‐tip stress field renders transformation‐toughened materials particularly susceptible to stress‐corrosion cracking. This interrelation leads to the definition of a steady‐state velocity at constant applied stress intensity factor. This velocity is obtained in the situation where the shielding term is fully defined by the present crack‐tip stress field, not depending on prior loading history.