Deformation and fracture behavior of Nb in Nb{sub 5}Si{sub 3}/Nb laminates and its effect on laminate toughness
- Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering
The mechanical behavior of the Nb reinforcement (250 {mu}m thick foils) in Nb{sub 5}Si{sub 3}/Nb/Nb{sub 5}Si{sub 3} laminates were investigated under a variety of stress states and test temperatures. Tests were conducted at room temperature (298 K) and 77 K on as-received Nb foils, on Nb{sub 5}Si{sub 3}/Nb/Nb{sub 5}Si{sub 3} laminates, on Nb foils extracts from the hot pressed laminates, and on Nb foils simply exposed to vacuum at high temperature. It is shown that Nb grain size, and solid solution of Si in Nb, degree of constraint, and test temperature significantly affect the mechanical behavior of Nb. All unconstrained Nb foils failed via ductile rupture at room temperature, while a mixture of cleavage and ductile fracture was exhibited by the constrained Nb present in the laminates. A similar ductile-to-brittle transition in fracture appearance was observed for some foils tested at 77 K, accompanied by a reduction in total energy to fracture. The peak toughness exhibited by the laminates tested at 77 K was only reduced 28% from that exhibited at 298 K, despite this drastic change in fracture mode from ductile to brittle. The effects of composition, interface strength and test conditions on the mechanical behavior of the Nb and its subsequent role on the toughness of the laminates are discussed.
- OSTI ID:
- 55345
- Journal Information:
- Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 5 Vol. 43; ISSN 0956-7151; ISSN AMATEB
- Country of Publication:
- United States
- Language:
- English
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