The purpose of this study was to obtain pure nanostructured titanium by drawing at cryogenic temperatures and to investigate its structural and mechanical properties. Titanium rods were obtained by severe plastic deformation under the scheme of upsetting-extrusion-drawing. Upsetting and extrusion were performed at 800 K, obtained rod was initially drawn at 300 K to diameter of 3.7 mm (degree of true strain e = 3.2). Further deformation of the finish drawing was performed at 77 K (liquid nitrogen) and at 300 K.Keywords: titanium / medical implants / plastic deformation / nanostructure / mechanical properties / Das Ziel dieser Arbeit war die Herstellung von reinem nanostrukturiertem Titan durch die Tiefzieh-Verformung bei kryogenen Temperaturen und die Untersuchung seiner strukturellen und mechanischen Eigenschaften. Titanproben (Stäbe) wurden durch die starke plastische Verformung beim Pressen-Extrusions-Tiefziehen hergestellt. Das Pressen und die Extrusion wurden bei 800 K durchgeführt, der erhaltene Stab wurde zuerst bei 300 K zu einem Durchmesser von 3,7 mm gezogen (wahre Dehnung e = 3,2%). Eine weitere endgültige Verformung wurde durch Tiefziehen bei 77 K (flüssiger Stickstoff) und bei 300 K durchgeführt.
The effect of low temperature (77 K) deformation by drawing (80%) on the superconducting properties and structure of vanadium is studied. The structural elements (fragment boundaries) responsible for the observed changes of critical parameters are isolated. The electron-phonon coupling constant and the electron mean free path undergo most significant changes in these regions of rotational deformation localization, which have a high density of defects and are powerful sources of internal stresses. The dislocation density at the fragment boundaries is estimated.
The effect of combined deformation, including equal-channel multiangle pressing (ECMAP), low-temperature (77 K) drawing, and thermal processing, on the critical current density of superconducting wires based on Nb-Ti alloys is investigated. Reasonable parameters are established for deformation-thermal processing of NT-50 alloy using ECMAP that will ensure improved functionality of superconductors based on this alloy. Vortex pinning on structural inhomogeneities of these alloys is analyzed qualitatively.
The structural state of iodide titanium after deformation by drawing at 77 K, which is the final stage of severe plastic deformation (SPD), has been analyzed and estimated in this work. The SPD has been implemented by a sequential combination of deformation techniques (compression-squirting-extrusion-drawing) that provide different stress epures. The temperature dependence of the logarithmic damping decrement of torsional oscillations in the 77-250 K temperature range has been studied to give a physical interpretation of the nonmonotonic change in the strength of the iodide titanium after SPD and to compare the calculated strength with that obtained for low purity titanium.
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