Zr, Zircaloy-4, Zr-Nb 합금의 미세조직 및 재결정 거동에 관한 연구

이명호; 최병권; 백종혁; 정용환; M.H. Lee; B.K. Choi; J.H. Baek; Y.H. Jeong

Korean Journal of Materials Research, Vol.10, No.6, 422-429, June, 2000

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Zr, Zircaloy-4, Zr-Nb 합금의 미세조직 및 재결정 거동에 관한 연구

A Study on the Recrystallization Behavior and Microstructure of Zr, Zircaloy-4 and Zr-Nb Alloys

이명호, 최병권, 백종혁, 정용환

한국원자력연구소 키르코늄 신합금 핵연료피복관 개발팀

M.H. Lee, B.K. Choi, J.H. Baek, and Y.H. Jeong

Advanced Zr Alloy Development, Korea Atomic Energy Research Institute, Korea

초록

Zr 합금의 재결정 거동 및 미세조직 변화에 미치는 열처리 온도 및 시간의 영향의 조사하기위하여 순수 Zr과 Zircaloy-4, Zr-0.88n-0.4Nb-0.4Fe-0.2Cu, Zr-1Nb 합금을 냉간가공한 후 400 ? C ~ 900 ? C 에서 각각 30분~5000분 동안 열처리하였다. 열처리 온도에 따른 Zr합금의 경도, 미세조직 및 석출물 특성을 미소경도기, 광학 현미경 및 투과 전자 현미경을 이용하여 조사하였다. 냉간 가공채는 400 ? C 에서 600 ? C 범위에서 재결정이 일어났는 데 합금원소가 증가함에 따라 재결정온도가 상승했고 결정립 성장이 억제되었다. 그리고 합금원소 증가에 따른 경도증가 영향이 재결정 이후에도 지속되었다. 열처리 온도 및 시간에 비례하여 재결정 이후 결정립 크기는 증가한 반면 경도변화는 상대적으로 미미하였다. Fe나 Cu가 Zr에 첨가될 경우 회복중 경도증가가 수반되는데, 이는 회복중 생성과 관련이 있는 것으로 사료된다.

To investigate the effect of annealing temperature and time on the recrystallization behavior and microstructure of Zr-based alloys, the specimens of Zr-0.8Sn-0.4Nb-0.4Fe-0.2Cu, Zr-1Nb, Zircaloy-4, and unalloyed Zr were cold-worked and annealed at 400, 500, 600, 700, 800, 900 ? C for 30 to 5000 minutes. The hardness, microstructure and precipitate of the specimens were investigated by using micro-hardness tester, optical microscope and transmission electron microscope, respectively. The recrystallization of Zr-based alloys occurred between 400 ? C and 600 ? C . As the content of alloying elements increased, the hardness and recrystallization temperature of the alloys increased though the grain sizes after recrystallization decreased. It was supposed that the hardness of Zr-based alloy with Fe or Cu increased during recovery by the formation of Fe or Cu precipitates.

Keywords:Zr-based alloys;Zircaloy-4;Zr-Nb alloys;recrystallization;grain growth;microstructure;annealing

[References]

Development of Cladding Materials for High Burn-up Fuel, Jeong YH, KAERI Report, KAERI/RR-1580/95/ KAERI, 1995 (1995)
Jeong YH, Kim CH, J. Kor. Inst. Met. Mater., 33, 682 (1995)
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Lim YS, Choi YJ, Kim HG, Jeong YH, Wey MY, J. Kor. Inst. Met. Mater., 37, 910 (1999)
King AD, Hood GM, Holt RA, J. Nucl. Mater., 185, 174 (1991)
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[Related Articles]

[1] Development of Cladding Materials for High Burn-up Fuel, Jeong YH, KAERI Report, KAERI/RR-1580/95/ KAERI, 1995 (1995)

[2] Jeong YH, Kim CH, J. Kor. Inst. Met. Mater., 33, 682 (1995)

[3] Jeong YH, Kim KH, J. Corros. Sci. Soc. of Korea, 25, 160 (1996)

[4] Mardon JP, et al., Proceeding of the 1997 International Topical Meeting on LWR Fuel Performance/ pp.405, 1997 (1997)

[5] Recovery and Recrystallization of Zirconium and It's Alloys, Bush SH, Kemper RS, Gray DL, W-69678, UC-25, Metals, Ceramics and Materials, (TID-4500, 16th Ed.)/ Hanford Atomic Products Operation, pp.5, 1961 (1961)

[6] Cotterill P, Mould PR, Recrystallization and Grain Growth in Metals/ Halsted Press Book, John Wiley & Sons, pp.15, 1976 (1976)

[7] Lim YS, Choi YJ, Kim HG, Jeong YH, Wey MY, J. Kor. Inst. Met. Mater., 37, 910 (1999)

[8] King AD, Hood GM, Holt RA, J. Nucl. Mater., 185, 174 (1991)

[9] Kidson GV, Electrochemical Technology, 4, 193 (1966)