Preparation and characterization of {100}<001> cube textured Ag substrates for in-plane oriented HTS tapes

A systematic study of texturing mechanisms in pure Ag is presented, the goal being to obtain a cube textured {100} <001> tape that can be used as a substrate for superconducting coated conductors. It is shown that a sharp cube texture can be produced after pre-heated deformation and recrystallization. Optimal parameters are detailed. 99.99% pure Ag powder is used as starting material. Fine grained (15 μm) Ag ingots are pre-heated at 100 deg. C before standard cold rolling. The effect of pre-heating on deformation texture is to change the main texture from the brass orientation {110}<112> to the Goss {110}<001> one. The presence of a copper-type texture with relatively high values of the ODF (oriented distribution function) after the 100 deg. C pre-heated deformation can be understood as a slight increase of the stacking fault energy of Ag during the pre-heated deformation. The optimal annealing is achieved at 700 deg. C for 30 min in a primary vacuum. This leads to a sharp cube texture. The FWHM values of the three x-ray pole figures are, at no more than 10 deg., the smallest ever reported for cube textured Ag tapes. The formation of cube texture is interpreted in terms of orientation nucleation and orientation growth theories that play a common role during the texturing process. The stability of cube texture at high temperature up to 900 deg. C indicates that the tapes are suitable for epitaxial growth of superconducting oxides. (author)