Creep and fracture in model niobium-alumina laminates under shear loading

Journal Article · Wed Jun 01 00:00:00 EDT 1994 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(94)90032-9· OSTI ID:7276522

Wu, X; Holmes, J W; Ghosh, A K ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States)

A simple experimental technique was developed to study the near-interface deformation and fracture behavior in ductile-phase-toughened brittle-matrix laminates subjected to elevated-temperature shear loading. In the study, specimens of Nb-foils bonded to Al[sub 2]O[sub 3] blocks were subjected to shear loading parallel to the Nb/Al[sub 2]O[sub 3] interfaces. The fracture path was controlled by the applied stress, the temperature and the thickness of the ductile Nb layers. At high shear stresses failure took place by brittle fracture within the Al[sub 2]O[sub 3] phase with concurrent shear creep in the Nb, and multiple crack branching/arresting toward the interface. At lower stresses, shear-creep and ductile fracture within the Nb were the dominant damage modes. Shear deformation was found to localize along the mid-plane of the Nb, due to strengthening of the Nb adjacent to the interface via solid solution and precipitation resulting from interdiffusion. With thin 20 [mu]m Nb-layers the fracture energy was low, similar to that found for pure Al[sub 2]O[sub 3]. The findings suggest that the ductile-phase toughening of laminated brittle matrix composites depends critically on the thickness of the ductile phase. A concept of brittle-ductile transition to assist in the understanding of the toughness enhancement provided by ductile phase additions into a brittle matrix.

• OSTI ID: 7276522
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 42:6; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BRITTLE-DUCTILE TRANSITIONS
CHALCOGENIDES
COMPOSITE MATERIALS
CREEP
DATA
DEFORMATION
EXPERIMENTAL DATA
FRACTURE PROPERTIES
INFORMATION
MATERIALS
MECHANICAL PROPERTIES
NIOBIUM ALLOYS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS