GROWTH CHARACTER OF Nb_3Sn TRANSFORMED FROM Nb_6Sn_5
Nb_6Sn_5生成Nb_3Sn的生长特性

The diffusion process of Sn in the transformation of Nb_6Sn_5 to Nb_3Sn has been studied. The experimentel results show that the growth of Nb_3Sn layer is controlled by two processes, i. e. the short range diffusion of Sn which is respon- sible for the inner layer with large grains, and the long range diffusion of Sn which results in the outer layer with fine grains. It was found that grain size depends on the reaction temperature. A model of Nb_3Sn growth based on the above processes was established and its solution was found to be in good agreement with experimen- tal results.