| Microstructural Characterization of Nitinol Stents | ||
| Dr. Ming H. Wu1, Prof Alejandro Toro2, Dr. William Van Geertruyden3, Prof Wojciech Z. Misiolek4 and Prof Xiaodong Han5, 1Memry Coporation, 3 Berkshire Blvd., Bethel, CT 06801, 2National University of Colombia, Cra 80 N, Medllin, 65-223, Colombia, 3EMV Technologies, LLC, 115 Research Drive, Bethlehem, PA 18015, 4Institute of Metal Forming, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, 5Solid Microstructure & Property Research Institute, Beijing University of Technology, Ping Le Yuan #100, Beijing, 100022, China
MICROSTRUCTURAL CHARACTERIZATION OF NITINOL STENTS A. Toro1, W. Van Geertruyden2, W.Z. Misiolek3, X.D. Han4 and M.H. Wu5
AbstractNitinol self-expanding stents are widely used in peripheral vascular interventions. These stents are generally manufactured from Nitinol tubing by laser micro-machining, followed by shape setting and electropolishing. A detailed study of the microstructural features in NiTi stents was performed, which included crystallographic texture analysis as well as TEM examination to determine the grain structure and precipitation kinetics. The samples were extracted from vascular stents, as well as from the parent tubes. Care was taken to avoid changes in the microstructure derived from mechanical polishing during the specimen’s preparation for EBSD observation, while the Focused Ion Beam (FIB) equipment was used for preparation of TEM discs. The specimens were analyzed at different stages of the stent production process, and correlations between the microstructure and the manufacturing process were established. Characterization of the main morphologic features of various phases was based on TEM imaging, and the effect of the different processing steps on the crystallographic texture was determined by adequate selection of samples location. Key Words: Nitinol stent, stent manufacturing, laser cutting, texture, microstructures. | ||