An origin of corrosion resistance changes of Zr alloys: effects of Sn and Nb on grain boundary strength of surface oxide

• DOI: 10.1016/j.actamat.2021.116804
• Publication Date: 2021-03-14T05:00:29Z
• Authors: Rong Yuan; Yao-Ping Xie; Tong Li; Chen-Hao Xu; Mei-Yi Yao; Jing-Xiang Xu; Hai-Bo Guo; Bang-Xin Zhou
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract As nuclear fuel cladding, Zr alloys have need for a good corrosion resistance. For decades, several generations of Zr alloys with excellent corrosion resistance have been developed through adjusting content of Sn and Nb. However, the mechanism of Sn and Nb influencing the corrosion resistance is still not clear. Here, our computational simulations indicate, Sn or Nb can segregate at grain boundary (GB) of surface oxide film which results in variation of GB cohesion and influences the corrosion resistance. Using the first-principles method, we find that Sn segregation reduce GB cohesion and decrease oxide film protectiveness; In contrast, Nb segregation enhance GB cohesion and improve oxide film protectiveness. The results are well consistent with the previous experiments that reducing Sn or adding Nb can promote corrosion resistance of Zr alloys. These findings provide a basis for understanding the roles of alloying elements in the corrosion resistance of Zr alloys, which is useful to future design of new Zr alloys.