51Cr diffusion in Zr-Sn alloys

The volume diffusion of 51Cr in Zr-Sn alloys was measured in coarse-grained polycrystals, using the ''thin film'' method. The Sn content in the alloys ranged from 0.39 to 6.7 at%. In the #betta#-phase, diffusion temperatures were between 9820C and 12400C. Sn was found to reduce the 51Cr diffusion in the #betta#-phase, the effect being small but well defined. The linear dehancement coefficient b and its temperature dependence were calculated, assuming the formation of Sn-Cr dimers. For the more dilute alloys Q and D0 were determined and upon application of the Zener theory for D0, a negative contribution to the activation entropy was found. In the α-phase where three experiments were done at different temperatures, 51Cr was shown to be a very fast-diffusing solute. No definite correlation with the Sn content was found probably owing to the anisotropy of the α-phase. (orig.)