The fracture toughness of niobium-based, in situ composites

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/BF02652346· OSTI ID:382504

Chan, K S ^[1]

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1. Southwest Research Inst., San Antonio, TX (United States)

The fracture resistance of Nb-Cr-Ti alloys or in situ composites of three different compositions, Cr{sub 2}Nb, and a Nb-10Si in situ composite was studied at ambient temperature. The crack-tip deformation and fracture behaviors were characterized using near-tip measurement techniques and fractographic analyses. The relevant fracture and toughening mechanisms were identified and related to the microstructure. Despite fracture by a combination of cleavage and slip band decohesion, the Nb solid-solution alloy exhibited a resistance-curve behavior with a relatively high toughness and local ductility. The source of toughness was modeled and explained in terms of a cracking process that involved alternate slip band decohesion and cleavage. The in situ composites, on the other hand, exhibited cleavage fracture but considerably lower toughness with little or no resistance-curve behaviors. The difference in the fracture behavior appears to arise from two factors: (1) the presence of a high constraint in the Nb solid-solution matrix in the in situ composites, and (2) the lack of plastic flow associated with cleavage of the constrained Nb solid-solution matrix.

• Sponsoring Organization: USDOE
• OSTI ID: 382504
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 9 Vol. 27; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
CLEAVAGE
COMPOSITE MATERIALS
CRACKS
FRACTOGRAPHY
FRACTURE MECHANICS
FRACTURE PROPERTIES
GAS TURBINE ENGINES
INTERMETALLIC COMPOUNDS
NIOBIUM ALLOYS
SILICON ALLOYS
SLIP
SOLID SOLUTIONS
TITANIUM ALLOYS