Diffusion of Interstitial Elements in Ti Alloys Used as Biomaterials

Abstract

Titanium alloys are excellent implant materials for orthopedic applications due to their desirable properties, such as good corrosion resistance, low elasticity modulus, and excellent biocompatibility. The presence of interstitial elements (such as oxygen and nitrogen) causes strong changes in the material’s mechanical properties, mainly in its elastic properties. Study of the interaction among interstitial elements present in metals began with Snoek’s postulate, that a stress-induced ordering of interstitials gives rise to a peak in the mechanical relaxation (internal friction) spectra. In the mechanical relaxation spectra, each species of interstitial solute atom gives rise to a distinct Snoek’s peak, whose temperature and position depend on the measurement frequency. This effect is very interesting because its peculiar parameters are directly related to the diffusion coefficient (D) for the interstitial solute. This paper presents a study of diffusion of heavy interstitial elements in Ti-35Nb-7Zr-5Ta alloys using mechanical spectroscopy. Pre-exponential factors and activation energies are calculated for oxygen and nitrogen in theses alloys.

Mechanical Spectroscopy of Ti-15Zr-based Alloys with Mo Addition

“…This heightened mobility may be a result of the low atomic radius of the Mo that allows it to increase /s for oxygen and nitrogen in the Ti-15Mo alloy, with the values dependent to the interstitial concentrations. Therefore, this study supports the assumption that the interstitial diffusivity and relaxation time depend on the interstitial and substitutional contents of the alloy 11,20 .…”

“…The activation energy of metal-gas interactions was obtained from previous studies with binary system alloys 3,4 . Diffusion parameters were obtained from the internal friction data, following procedures detailed in the literature 11 , and using crystalline structural parameters obtained by XRD measurements in previous reports (Table 1) 10 .…”

Diffusion of Oxygen and Nitrogen in the Ti-15Mo Alloy Used for Biomedical Applications

“…In the mechanical relaxation spectra, each species of interstitial solute atoms gives rise to a distinct Snoek's peak, whose temperature and position depend on the measurement frequency. This effect is very interesting because its peculiar parameters are directly related to the diffusion coefficient (D) of the interstitial solute [6,8].…”