Fracture toughness and R-curve behavior of laminated brittle-matrix composites

Journal Article · Thu Oct 01 04:00:00 EDT 1998 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-998-0220-0· OSTI ID:669742

Bloyer, D R; Ritchie, R O ^[1]; Rao, K T.V. ^[2]

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1. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering
2. Univ. of California, Berkeley, CA (United States)

The fracture toughness and resistance-curve behavior of relatively coarse-scale, niobium/niobium aluminide (Nb/Nb{sub 3}Al) laminated composites have been examined and compared to other Nb/Nb{sub 3}Al composites with (in situ) Nb particulate or microlaminate reinforcements. The addition of high aspect-ratio Nb reinforcements, in the form of 20 vol. pct of 50- to 250-{micro}m-thick layers, was seen to improve the toughness of the Nb{sub 3}Al intermetallic matrix by well over an order of magnitude, with the toughness increasing with Nb layer thickness. The orientation of the laminate had a small effect on crack-growth resistance with optimal properties being found in the crack arrester, as compared to the crack divider, orientation. The high fracture toughness of these laminates was primarily attributed to large ({approximately}1- to 6-mm) crack-bridging zones formed by intact Nb layers in the crack wake; these zones were of sufficient size that large-scale bridging (LSB) conditions generally prevailed in the samples tested. Resistance-curve modeling using weight function methods permitted the determination of simple approximations for the bridging tractions, which were then used to make small-scale bridging (SSB) predictions for the steady-state toughness of each laminate.

• Sponsoring Organization: USDOE
• OSTI ID: 669742
• 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: 10 Vol. 29; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COMPOSITE MATERIALS
CRACKS
FRACTURE MECHANICS
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
LAYERS
NIOBIUM
NIOBIUM ALLOYS
PARTICULATES