Fracture toughness and fatigue crack growth in rapidly quenched Nb-Cr-Ti in situ composites

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

DOI:https://doi.org/10.1007/s11661-997-0110-x· OSTI ID:544055

Chan, K S; Davidson, D L ^[1]; Anton, D L ^[2]

---

1. Southwest Research Inst., San Antonio, TX (United States)
2. United Technologies Research Center, East Hartford, CT (United States)

In situ composites based on the Nb-Cr-Ti ternary system were processed by rapid solidification in order to reduce the size of the reinforcing intermetallic phase. Two-phase microstructures with small Cr{sub 2}Nb particles in a Nb(Cr, Ti) solid solution alloy matrix were produced for several compositions that previous work showed to produce high toughness composites in cast materials. The fracture and fatigue behaviors of these composites were characterized at ambient temperature. The results indicate that the fracture resistance increases with a decreasing volume of Cr{sub 2}Nb particles. Fracture toughnesses of the rapidly solidified materials with their smaller particle sizes were lower than for conventionally processed composites with larger particles of the intermetallic compound. The fatigue crack growth rate curves exhibit steep slopes and a low critical stress intensity factor at fracture. The lack of fracture and fatigue resistance is attributed to the continguity of the intermetallic particles and the absence of plastic flow in the Nb solid solution matrix. The matrix alloy appears to be embrittled by (1) the rapid solidification processing that prevented plastic relaxation of residual stresses, (2) a high oxygen content, and (3) the constraint caused by the hard Cr{sub 2}Nb particles.

• Sponsoring Organization: Department of the Air Force, Washington, DC (United States)
• OSTI ID: 544055
• 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. 28; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
COMPOSITE MATERIALS
CRACK PROPAGATION
FATIGUE
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NIOBIUM ALLOYS
PARTICLE SIZE
SOLID SOLUTIONS
TITANIUM ALLOYS