Commercially pure nanostructured titanium for biomedicine and a method for making a bar thereof

摘要

Commercially pure titanium having UFG structure and enhanced mechanical and biomedical characteristics has nanocrystalline alpha-phase grains with a hexagonal close-packed lattice, in which the share of grains with a size of 0.1...0.5 µm and a grain shape coefficient of no more than 2 in the mutually perpendicular planes makes no less than 90%, over 60% of the grains having high-angle boundaries disoriented in relation to the adjacent grains by the angles from 15 to 90°. The method for making a rod of the material provides for equal-channel angular pressing_of a billet at T ‰¤ 450°C with the total accumulated true strain e ‰¥ 4 to effect severe plastic deformation of the billet and subsequent thermomechanical treatment with a gradual decrease of the temperature in the range of 450...350°C and the strain rate of 10 -2 ...10 -4 s -1 with the strain degree from 40 to 80% to effect additional plastic deformation.