| Abstract |
| The effects of β phase decomposition on recrystallization and texture variation in Zr-2.5% Nb alloy pressure tube material were investigated. Isothermal annealing was conducted at 350 to 550 ℃ for 240 hours, and isothermal annealing was performed at 500 ℃ for 240 to 3,000 hours. The recrystallization and texture variation were analyzed by inverse pole figure variation using the XRD and EBSD methods. Annealing in α-Zr region at below 610 ℃ induced recrystallization and texture variation in the α-Zr. These results differ from those from a previous annealing study of the α+β region at 750-830 ℃. Annealing above 400 ℃ for 240 hours caused β-Zr decomposition into β-Nb. The decomposition of the β-phase by annealing above 475 ℃ caused a contraction of 7.5% in the d(110) spacing in the β-phase, and a reduction in the volume fraction of the β phase by about 80%. It seems that the stress internally formed by the lattice contraction of the β-phase provides the driving force for recrystallization. In addition, it suggests that the newly formed α-Zr produced by β phase decomposition provides new nucleation sites for recrystallization and causes texture variation in the α-Zr. The reason why the recrystallization and the texture variation occurs only in the α-Zr stable region at below 610 ℃ is discussed. |
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| Key Words |
| Zr-2, 5%Nb alloy, annealing, recrystallization, β phase decomposition, texture variation |
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