Tensile creep and rupture behavior along with evolution of microstructure in a Zr-2.5Nb alloy
IR@NML: CSIR-National Metallurgical Laboratory, Jamshedpur
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| Title |
Tensile creep and rupture behavior along with evolution of microstructure in a Zr-2.5Nb alloy
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| Creator |
Guguloth, K
Ghosh, M Swaminathan, J Mitra, R |
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| Subject |
Materials Science
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| Description |
Tensile creep behavior of the Zr-2.5Nb alloy has been studied through tests under constant load (stress range similar to 137-371 MPa) between 275 and 375 degrees C. The minimum creep rate of the alloy is found to vary with applied stress and temperature following a power-law relation. The values of stress exponent (n) obtained in the range of 5.3-6.8 in the temperature interval of 300-375 degrees C; whereas it is calculated as 1.2 and 7.0 under low and high stresses, respectively at 275 degrees C. The apparent activation energy of creep (Q(c)) and stress exponent have been determined by analyzing the experimental data. The obtained Q(c) (similar to 198.5 +/- 10.7 kJ/mol) is found to be higher than the lattice self-diffusion activation energy of pure zirconium (113 kJ/mol). Using this value, stress exponent similar to 5.6 +/- 0.23 is obtained by the temperature-compensated power law. Microstructural characterization by transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) analysis has confirmed coarsening of beta-(Nb, Zr) precipitates with compositional changes during creep. The dislocation-precipitate interaction as evidenced by TEM observations is considered to be the origin of threshold stress, which decreases with increasing temperature. Considering the threshold stress, true activation energy of creep (Q(t)) and true stress exponent (n(t)) are found as similar to 160.4 +/- 6.9 kJ/mol and similar to 4.8 +/- 0.22, respectively. Analysis of creep data has confirmed the role of dislocation climb as the rate-controlling mechanism, along with validity of Monkman-Grant and modified Monkman-Grant relations. Scanning electron microscopy (SEM) of creep fracture surfaces has revealed evidence for prominent ductile fracture. Further, the obtained creep damage tolerance factor value of 1.9, indicating the predominance for cavitation during creep.
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| Publisher |
Elsevier
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| Date |
2020
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://eprints.nmlindia.org/8214/1/gugloth-2020.pdf
Guguloth, K and Ghosh, M and Swaminathan, J and Mitra, R (2020) Tensile creep and rupture behavior along with evolution of microstructure in a Zr-2.5Nb alloy. Materials Science and Engineering A, 791 (IF- 4.652). p. 139681. |
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| Relation |
https://www.sciencedirect.com/science/article/pii/S0921509320307607
http://eprints.nmlindia.org/8214/ |
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