FRACTAL DIMENSION OF CAVITIES SHAPE CHANGES DURING SUPERPLASTIC DEFORMATION OF HIGH STRENGTH Al ALLOY 7475
高强度7475Al合金超塑变形空洞形状变化的分形描述

The fractal dimension changes of cavities have been determined duringsuperplastic deformation of the high strength Al alloy 7475 with different strain,temperature, strain rate and grain size. The fractal dimension of cavities may in-crease with the increase of strain. It becomes higher as the alloy deformed underthe lower temperature, the greater strain rate and the coarser grain size. The alloywould be approaching to rupture if the fractal dimension of cavities raised to acertain extent.