The 51Cr diffusion along grain boundaries in polycrystalline α-Zr was measured by means of the radiotracer technique at 449 to 680K. The use of Harrison´s C and B kinetics provided direct data about grain boundary diffusivity (Dgb) and the apparent grain boundary diffusivity (Pgb) in the temperature range of power-reactor service. The diffusion results (tables 4 and 5) obtained for type-B and type-C kinetics could be expressed as:

P(m3/s) = 4.4 x 10-9 exp[-126.0(kJ/mol)/RT]

D(m2/s) = 7.27 x 102 exp[-138.0(kJ/mol)/RT]

The grain boundary segregation factor of Cr in α-Zr was determined in the limit of very dilute solute concentration.

Grain Boundary Diffusion and Segregation of Cr in α-Zr. C.C.Moya, M.J.Iribarren, N.Di Lalla, F.Dyment: Journal of Nuclear Materials, 2008, 382[1], 35-8

Table 5

Grain-Boundary Diffusion of Cr in α-Zr (Type-C Kinetics)