HIGH-STRAIN, HIGH-STRAIN RATE DEFORMATION, SHEAR LOCALIZATION AND RECRYSTALLIZATION IN TANTALUM

Tantalum tubular specimens, embedded in copper thick-wall cylinders, w ere collapsed quasi-uniformly by detonating the explosive in co-axial with the copper cylinder. The microstructure featured: (i) dislocation s and elongated dislocation cells; (ii) subgrains; (iii) dynamically r ecrystallized micrograins; and (iv) statically recrystallized grains w hose grain sizes were predicted using conventional grain-growth kineti cs. The evolution mechanism of the microstructure from elongated dislo cation cells, subgrains, to micrograins is proposed Grain-scale locali zation was observed Ductile fracture along shear bands was produced by the residual tensile hoop stresses near the central hole region upon unloading.