METHOD OF FABRICATION OF NANOCRYSTALLINE TITANIUM, IN PARTICULAR FOR MEDICAL IMPLANTS, AND TITANIUM MEDICAL IMPLANT

摘要

The method consists of subjecting a coarse-grained titanium semi-product (1) with the pure titanium content of at least 99wt% to a plastic deformation. In said plastic deformation the transverse cross-section surface area of the titanium semi-product is reduced by hydrostatic extrusion in which the titanium semi-product is the billet (1) extruded through the die (4). The reduction (R) of the transverse cross-section of the titanium billet (1) is realized in at least three but not more than five consecutive hydrostatic extrusion passes at the initial temperature of the billet (1) not above 50º C and the extrusion velocity not above 50 cm/s. Prior to each hydrostatic extrusion pass, the titanium billet is covered with a friction-reducing agent. During the first hydrostatic extrusion pass, the reduction of the transverse cross-section surface area of the titanium semi-product is at least four, whereas during the second and third hydrostatic extrusion pass it is at least two and a half. The titanium medical implant contains at least 99wt% of pure titanium. The material of the implant has a nanocrystalline structure with an average grain size below 100nm, and the yield stress exceeding 1000 MPa.