Papers by Keyword: Low Elastic Modulus

Abstract: The excellent biocompatibility of Ti and Zr alloys makes them the best candidates for orthopedic implantations. The design of high Ti and Zr-containing alloys that show low Young's modulus for implant manufacturing is the objective of this work. Here, a feed-forward-back propagation neural network was used to speed up the design process and optimize alloy composition. The β-typeTi₄₅-Zr₃₉-Nb₁₂-Mo₄ alloy is designed and showed promising properties. The alloy showed a low elastic modulus of 78 GPa and a high yield strength of 891 MPa resulting in a high elastic admissible strain that made it suitable for orthopedic applications.

Abstract: Superelastic biocompatible metallic materials Ti-22Nb-6Zr and Ti-22Nb-3Ta-3Zr (at %) were produced. Vacuum arc remelting (VAR) with manual control allowed to produce high‑purity alloys. X-ray fluorescence spectrometry (XRF) results showed that one remelt was not enough to obtain homogeneous Ti-Nb-Ta-Zr ingot. Ti-Nb-Zr and Ti-Nb-Ta-Zr alloys were remelted 3 times and turned upside down after each remelting. Scanning electron microscopy (SEM) with micro X‑ray spectral analysis showed that chemical composition of the alloys coincided with nominal chemical composition. SEM results also showed that the alloys were mostly homogeneous. Recommendations for optimization of VAR in terms of producing high-purity homogeneous superelastic titanium alloys were elaborated.

Abstract: Ti-Al-Mo-Fe alloys were developed as low cost beta Ti alloys for automotive springs, and designed based on Molybdenum equivalency and Bo-Md molecular orbital method. Low priced Mo-Fe master alloys were introduced as alloying elements for the cost and elastic modulus reduction. Eight Ti-Al-Mo-Fe alloy candidates were pre-designed according to the Bo-Md method. Primary laboratory scale ingots were thus melted by ISM (Induction Skull Melting). After primary property evaluation, the Ti-2Al-9.2Mo-2Fe alloy was optimized finally and large scale ingot was made by VAR for further property evaluation. Resultantly, it shows that the alloy has lower elastic modulus (60-70 GPa) and good tensile properties in the solution condition, and compares well with the other developed commercial beta alloys.

Abstract: Nowadays, β type Ti-based alloys have been developed for load transfer clinical applications due to their superelasticity, shape memory effect, low elastic modulus and high damping capacity [1]. These properties promote bone regeneration and make them promising candidates for being used in load transfer implantology. The objective of the present work is to achieve a material with shape memory properties and/or low elastic modulus. The influence of cold work on the thermoelastic martensitic transformation and elastic modulus of the Ti-16.2Hf-24.8Nb-1Zr alloy has been investigated to determine optimal conditions. The homogenized vacuum arc melted button was heat treated at 1100°C during 2 hours and quenched. Samples of each alloy were microstructurally and mechanically characterized after being cold rolled from 5 up to 95%. The elastic response for each condition was evaluated by instrumented nanoindentation by using a Berkovich tip and a spherical tip. A decrease in elastic modulus was observed when increasing the cold work percentage. The lowest value, 44 GPa, similar to that of cortical bone, was found in the 95% cold worked condition.

Abstract: New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of an artificial prosthesis. The newly developed alloys contained the transition elements like Zr, Hf, Nb, Ta which were non-cytotoxicity elements and β stabilizers. In the present paper the elastic moduli of Ti-xM containing Zr, Hf, Nb, Ta were evaluated by measuring the velocity of supersonic wave (Pulse Echo Overlap). The effectiveness of the alloying elements for lowering the elastic modulus was investigated. In addition, the dominant factors for the low modulus were discussed. Ta was the most effective in lowering the elastic modulus of the alloys. The effectiveness of Hf was not acceptable for decreasing the elastic modulus. The dominant factor was the lattice parameter for Zr, and the poisson's ratio for Nb, Ta, respectively, in lowering the elastic modulus of Ti.

Abstract: New titanium alloys with a low elastic modulus have been developed for biomedical applications to avoid the stress shielding effect of the artificial prosthesis. The newly developed alloys contained the transition elements like Nb, Ta, Zr which were non-cytotoxicity elements. These elements produced β, ω, and α'' phases with heat treatment conditions in titanium alloys and determined the elastic modulus of the alloys. However, the clear mechanism of the low elastic modulus alloys has not been known. In the present paper, the total energy and elastic modulus of β and α'' phases were calculated using a first principle calculation employing the generalized gradient approximation (GGA). The mechanism of the low elastic modulus was discussed with calculated values.