J Mater Sci Technol ›› 2012, Vol. 28 ›› Issue (7): 606-613.

• High Temperature Structural Materials • Previous Articles     Next Articles

Optimization of N18 Zirconium Alloy for Fuel Cladding of Water Reactors

B.X. Zhou1,2), M.Y. Yao1,2), Z.K. Li3), X.M. Wang4), J. Zhou3), C.S. Long4), Q. Liu5), B.F. Luan5)   

  1. 1) Laboratory for Microstructures, Shanghai University, Shanghai 200444, China
    2) Institute of Materials, Shanghai University, Shanghai 200072, China
    3) Northwest Institute for Non-ferrous Metal Research, Xi′an 721014, China
    4) Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu 610041, China
    5) College of Material Science and Engineering, Chongqing University, Chongqing 400044, China
  • Received:2011-11-20 Revised:2012-02-25 Online:2012-07-28 Published:2012-07-26
  • Contact: B.X. Zhou
  • Supported by:

    the National Natural Science Foundation of China (Nos. 50871064 and 50971084) and Shanghai Leading Academic Discipline Project (No. S30107)

Abstract: In order to optimize the microstructure and composition of N18 zirconium alloy (Zr–1Sn–0.35Nb–0.35Fe–0.1Cr, in mass fraction, %), which was developed in China in 1990s, the effect of microstructure and composition variation on the corrosion resistance of the N18 alloy has been investigated. The autoclave corrosion tests were carried out in super heated steam at 400 °C/10.3 MPa, in deionized water or lithiated water with 0.01 mol/L LiOH at 360 °C/18.6 MPa. The exposure time lasted for 300–550 days according to the test temperature. The results show that the microstructure with a fine and uniform distribution of second phase particles (SPPs), and the decrease of Sn content from 1% (in mass fraction, the same as follows) to 0.8% are of benefit to improving the corrosion resistance; It is detrimental to the corrosion resistance if no Cr addition. The addition of Nb content with upper limit (0.35%) is beneficial to improving the corrosion resistance. The addition of Cu less than 0.1% shows no remarkable influence upon the corrosion resistance for N18 alloy. Comparing the corrosion resistance of the optimized N18 with other commercial zirconium alloys, such as Zircaloy-4, ZIRLO, E635 and E110, the former shows superior corrosion resistance in all autoclave testing conditions mentioned above. Although the data of the corrosion resistance as fuel cladding for high burn-up has not been obtained yet, it is believed that the optimized N18 alloy is promising for the candidate of fuel cladding materials as high burn-up fuel assemblies. Based on the theory that the microstructural evolution of oxide layer during corrosion process will affect the corrosion resistance of zirconium alloys, the improvement of corrosion resistance of the N18 alloy by obtaining the microstructure with nano-size and uniform distribution of SPPs, and by decreasing the content of Sn and maintaining the content of Cr is discussed.

Key words: Zirconium alloys, Corrosion resistance, Composition variation, Microstructure