Dependence of grain and subgrain size during superplastic deformation of a powder metallurgy pure aluminum 1N90

High strain rate superplasticity was obtained for a powder metallurgy pure aluminum, 1N90. The material exhibited the grain sizes of 15.2 μm with the subgrains of 1 μm before superplastic deformation. The microstructure of the material did not change much after superplastic deformation. Present result indicates that the subgrains with the misorientation angle >5° play an important role through boundary sliding during superplastic deformation. The optimum stain rate was depended on subgrain size with misorientation angles more than 5°, not grain size. This is a new phenomenon which never reported before.