Slow crack growth behavior in transformation-toughened Al/sub 2/O/sub 3/-ZrO/sub 2/(Y/sub 2/O/sub 3/) ceramics

Journal Article · Fri Jul 01 00:00:00 EDT 1983 · J. Am. Ceram. Soc.; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1983.tb10587.x· OSTI ID:6315265

Becher, P F

Significant increases in the critical fracture toughness (K/sub IC/) over that of alumina are obtained by the stress-induced phase transformation in partially stabilized ZrO/sub 2/ particles which are dispersed in alumina. More importantly, improved slow crack growth resistance is observed in the alumina ceramics containing partially stabilized ZrO/sub 2/ particles when the stress-induced phase transformation occurs. Thus, increasing the contribution of the ZrO/sub 2/ phase transformation by tailoring the Y/sub 2/O/sub 3/ stabilizer content not only increases the critical fracture toughness (K/sub IC/) but also the K/sub Ia/ to initiate slow crack growth. For example, crack velocities (n..mu..) greater than or equal to 10/sup -9/ m/s are obtained only at K/sub Ia/ greater than or equal to 5 MPa.m/sup 1/2/ in transformation-toughened (K/sub IC/ = 8.5 MPa.m/sup 1/2/) composites vs K/sub Ia/ greater than or equal to 2.7 MPa.m/sup 1/2/ for comparable velocities in composites where the transformation does not occur (K/sub IC/ = 4.5 MPa.m/sub 1/2/). This behavior is a result of crack-tip shielding by the dissipation of strain energy in the transformation zone surrounding the crack. The stress corrosion parameter n is lower and A greater in these fine-grained composite materials than in fine-grained aluminas. This is a result of the residual tensile stresses associated with larger (greater than or equal to 1 ..mu..m) monoclinic ZrO/sub 2/ particles which reside along the intergranual crack path.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6315265
• Journal Information: J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 66:7; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRACK PROPAGATION
FRACTURE PROPERTIES
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES