title: Cross-section transmission electron microscopy characterization of the near-surface structure of medical Nitinol superelastic tubing.
abstract: The application of Nitinol in a wide variety of medical implants is progressively increasing because of its unique mechanical properties, durability and biocompatibility. However, as Nitinol consists of about 50 at.% of toxic Ni, certain applications are still hindered by the concern of free Ni release in the surrounding tissue. The latter is controlled by the structure of near-surface layers and can be strongly affected by various surface treatments. A proper application of advanced cross-section sample preparation techniques allows us to characterize the Nitinol near-surface structure down to the nanoscale by means of transmission electron microscopy (TEM). Elemental maps of the Ti, O and Ni distribution, concentration profiles, quantification of composition as well as atomic resolution images at the surface of a Nitinol tubing are presented and the results obtained with different sample preparation and analytical characterization techniques are compared. In addition to a strong decrease of Ni towards the surface of the oxide layer and a Ti depleted layer underneath the oxide, also a possible transformation from TiO to TiO(2) is documented.
authors.affiliation: EMAT, University of Antwerp, Antwerp, Belgium.
authors.forename: Pavel L
authors.initials: PL
authors.lastname: Potapov
authors.forename: Wim
authors.initials: W
authors.lastname: Tirry
authors.forename: Dominique
authors.initials: D
authors.lastname: Schryvers
authors.forename: Valerie G M
authors.initials: VG
authors.lastname: Sivel
authors.forename: Meng-Yue
authors.initials: MY
authors.lastname: Wu
authors.forename: Dimitri
authors.initials: D
authors.lastname: Aslanidis
authors.forename: Henny
authors.initials: H
authors.lastname: Zandbergen
mesh_terms: D000497:Alloys / Q000737:chemistry / Q000633:toxicity; D001672:Biocompatible Materials / Q000737:chemistry / Q000633:toxicity; D004548:Elasticity; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008854:Microscopy, Electron; D009532:Nickel / Q000737:chemistry / Q000633:toxicity; D010084:Oxidation-Reduction; D019736:Prostheses and Implants; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; C013616:nitinol; D009532:Nickel; D014025:Titanium