Anisotropic hardness and fracture toughness of highly aligned YBa sub 2 Cu sub 3 O sub 7 minus. delta

Journal Article · Sun Mar 01 00:00:00 EST 1992 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.351090· OSTI ID:5002342

Goyal, A; Funkenbusch, P D; Kroeger, D M; Burns, S J ^[1]

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1. Materials Science Program, Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States)

The hardness and fracture toughness of aligned YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} obtained by melt processing was found to be highly anisotropic. Indentation measurements show that the (001), (100), and (010) planes are the preferred fracture planes in this material and that the critical stress intensity factor for propagating a crack on the (001) basal plane is the lowest, i.e., {ital K}{sub {ital c}}{sup 001}{lt}{ital K}{sub {ital c}}{sup 100} or {ital K}{sub {ital c}}{sup 010}. Indentation crack length measurements on the (001) basal plane with the impression diagonals oriented parallel to the (100) and the (010) directions, indicate that the fracture toughness of these planes is {ital K}{sub 100/010}{sup air}{similar to}0.7 MPa m{sup 1/2}. The hardness in this orientation was found to be 6.7 GPa. Measurements on a plane perpendicular to the basal plane resulted in a lower hardness of {similar to}3.8 GPa. This reduction in hardness is influenced by the extensive preferential cleavage of the (001) basal plane boundaries. The extremely low values of the fracture toughness suggest that considerable toughening would have to be achieved in melt-textured 123 for any practical bulk application. The presence of 211 phase and silver particles may serve to enhance the fracture toughness of aligned 123 by crack deflection and crack tip blunting respectively.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5002342
• Journal Information: Journal of Applied Physics; (United States), Vol. 71:5; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
FRACTURE PROPERTIES
HARDNESS
COPPER OXIDES
YTTRIUM OXIDES
ANISOTROPY
HIGH-TC SUPERCONDUCTORS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360203* - Ceramics
Cermets
& Refractories- Mechanical Properties