Fatigue crack growth through alloyed niobium, Nb-Cr{sub 2}Nb, and Nb-Nb{sub 5}Si{sub 3} in situ composites

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0266-4· OSTI ID:514759

Davidson, D L ^[1]

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

Fatigue cracks were grown through several niobium-based materials. For Nb-Cr-Ti composition materials, the single-phase alloy represented the matrix of two in situ composites with about 22 and 38 vol pct Cr{sub 2}Nb. Grain boundaries were coated with intermetallic in the lower-volume fraction material, while the 38 vol pct Cr{sub 2}Nb composite consisted of mainly spherical, dispersed intermetallic. The Nb-10Si composite was composed of about 28 vol pct primary Nb{sub 5}Si{sub 3}, with most of the matrix alloy in fiberlike shapes due to extrusion. Crack growth rates through the composites were generally faster than for unalloyed Nb, roughly in proportion to the volume fraction of intermetallic, although differences in microstructure make this comparison difficult. The presence of intermetallic greatly alters deformation of material near the crack tip. Particles of Cr{sub 2}Nb were broken during the crack growth process, leading to increased crack growth rates. These results suggest microstructural modifications that could be expected to enhance fatigue crack growth resistance.

• Sponsoring Organization: USDOE
• OSTI ID: 514759
• 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: 6 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM ALLOYS
COMPOSITE MATERIALS
CRACK PROPAGATION
FATIGUE
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NIOBIUM ALLOYS
NIOBIUM SILICIDES