Effects of Hydrogen Absorption on the Mechanical Properties of Zr-Nb Alloys
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1043-T09-08
Effects of Hydrogen Absorption on the Mechanical Properties of Zr-Nb Alloys Shunichiro Nishioka, Masato Ito, Hiroaki Muta, Masayoshi Uno, and Shinsuke Yamanaka Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan ABSTRACT Young’s moduli of hydrogenated Zr-Nb alloys were evaluated by using a multiple elastometer in the temperature range from room temperature to 773 K, based on the cantilever characteristic vibration technique. The decreasing rate of Young’s modulus against the temperature was independent on the additive amount of Nb. The Young’s modulus for the hydrogen solid solution of Zr-Nb alloys decreased and that those for the alloys with partially precipitated hydride slightly changed with increasing hydrogen content in both of Zr-1.0Nb and Zr-2.5Nb. The decreasing rates with hydrogen content of hydrogen solid solution of Zr-Nb alloys were almost same as that of Zr hydrogen solid solution. This result was considered because all specimens largely consisted of α-zirconium in which the solute hydrogen was found to decrease the Young’s modulus.
INTRODUCTION The surface of fuel cladding tubes used in light-water reactors oxidizes through corrosion reaction with coolant water and hydrogen is generated during operation. The hydrogen is partly absorbed by the claddings. Amount of hydrogen absorbed into claddings will increase with the burnup extension of light-water reactors. Therefore it is necessary to improve corrosion resistivity and mechanical properties of the cladding tube. The Zr-Nb alloys are expected for the new cladding tube materials and NDA, MDA and ZIRLO have been newly used to improve corrosion resistivity and mechanical properties. The corrosion resistivity of the cladding materials has been investigated while there are not so many studies of effects of hydrogen absorption on the basic properties of cladding materials [1 - 5]. Figure 1 shows the change in Young’s modulus for hydrogenated Zr with the hydrogen content which had been measured by our group in past years [6]. The solid marks indicated the results for the hydrogen solid solution and the open ones were those for alloys with the partially precipitated hydride. It was found that Young’s modulus for the hydrogen solid solution of Zr which had α single phase decreased with increasing hydrogen content. It was also found that Young’s modulus for Zr with the partially precipitated hydride which was (α + δ) biphasic slightly changed with increasing hydrogen contents. In this study, effects of hydrogen absorption on the mechanical properties of Zr-Nb alloys were evaluated and compared to those of pure Zr
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Young's modulus, E [GPa]
298 K 473 K 523 K 573 K 623 K 673 K 723 K 773 K Solid marks: solid solution
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Hydrogen content, CH [ppm]
Figure 1. Change in Young’s modulus E of hydrogenated Zr with hydrogen content, CH.
EXPERIMENTAL PROCEDURE The specimens of Zr–1.0 wt% Nb and Zr–2.5Nb were produced b
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