Quantitative description of damage evolution in ductile fracture of tantalum

Dynamic ductile fracture has been studied through incipient spallation expe riments on two grades of tantalum. A commercially pure Ta material incipien tly spalled at 252 m/s, a highly pure Ta material incipiently spalled at 24 6 m/s, and a highly pure Ta material preshocked at 250 m/s and incipiently spalled at 246 m/s were used. Microstructural parameters of the fracture pr ocess such as porosity, void-size distributions, and void aspect ratios hav e been quantified using image analysis and optical profilometry techniques. The commercially pure Ta,the highly pure Ta preshocked prior to spall, and the annealed high-purity Ta exhibited 27, 16.6, and 5.5 pet porosity, resp ectively. The void-size distribution observed in all three tests was adequa tely represented by either a log-normal or a linear combination of a log-no rmal and a Weibull distribution function. At least 80 pet of the aspect rat ios observed in all three tests were adequately represented by a gamma dist ribution function.