Effects of strain cycling on buckling, cracking and spalling of a thermally grown alumina on a nickel-based bond coat

Journal Article · Fri Jan 15 04:00:00 EST 1999 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00328-0· OSTI ID:329064

Wang, J S; Evans, A G ^[1]

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1. Harvard Univ., Cambridge, MA (United States). Div. of Engineering and Applied Sciences

Strain cycling has been used to study various events that occur in association with an alumina thin layer thermally grown on a Ni-based bond coat. There are three main findings. (i) Buckles propagate with a growth per cycle suggestive of effects of cycling on the friction acting at the separated interfaces. (ii) Cracking of the thermally grown oxide (TGO) occurs within buckles having high ellipticity, subject to a flexural strength typical of fine-grained Al{sub 2}O{sub 3}, with small stressed volume. Such cracking has implications for oxygen ingress and rapid degradation. (iii) Spalling occurs preferentially in those buckles that previously crack. The measurements are analyzed using the mechanics of buckle propagation, bending and kinking.

• OSTI ID: 329064
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 2 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CRACK PROPAGATION
FRACTURE PROPERTIES
INTERFACES
NICKEL BASE ALLOYS
STRAINS
STRESSES
SUBSTRATES
THIN FILMS