Dynamic tensile extrusion response of tantalum

The effects of the original rolling texture and impact velocity on the large-strain dynamic tensile extrusion process in a high-purity Ta have been investigated in a gas gun facility. A continuous increasing of the total elongation of the extruded Ta spheres with increasing impact velocities has been observed. The starting texture was found to influence the development of instabilities with little effect on the total elongation. Regardless of the starting textures and impact velocities, a strong <1 1 0> fiber texture was developed along the extrusion direction and similar hardness increments were recorded in the recovered Ta segments. Dislocation analysis revealed a continuous evolution of the dislocation substructures from loose planar arrays, to microbands, to elongated cells structures, and to equiaxed subgrains as a function of deformation. The evolution process of the dislocation substructures is discussed in detail in correlation with the development of the microstructure as well as the texture.