| Title |
Effect of β Phase Decomposition on Recrystallization in α-Zr Region in Zr-2.5%Nb Pressure Tube Material |
| Authors |
김성수(Sungsoo Kim); 임상엽(Sang Yup Lim); 이경근(Gyeong-geun Lee) |
| DOI |
https://doi.org/10.3365/KJMM.2020.58.10.672 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Zr-2; 5%Nb alloy; annealing; recrystallization; β phase decomposition; texture variation |
| 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. |