The microstructure of the starting materials characterized
by optical microscopy is shown in Fig. 2. It can be seen
clearly that the starting Zr702 is fully recrystallized with a
grain size of about 20m. However, after one pass deformation,
a typical lamellar deformation structure developed
as shown in Fig. 3. The angle between the direction of the
parallel boundaries and the ED is about 27◦. Comparing the
microstructures of Figs. 2 and 3,