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| The co-authors of the development, as well as specialists from the UrFU Department of Heat Treatment and Metal Physics. Photo Credit: Rodion Narudinov |
Scientists from Ural Federal University, Institute of Strength Physics and Materials Science of the SB RAS and National Research Tomsk Polytechnic University have tested new titanium-based alloys, which have several advantages over traditional medical ones. Two types of titanium alloys — TNZ (including niobium and zirconium) and multi-element TNZTS (with niobium, zirconium, tantalum and tin) — were subjected to uniaxial pressing and multi-pass rolling. As a result of exposure, ultrafine-grained structures were formed in the alloys, which significantly increased the strength and hardness of the material. The results of the research were published in the Materials Letters Journal.
Crystal structure of titan (α-phase) that formed after tests trial improved the strength characteristics of the TNZ-alloy, but at the same time reduced its plasticity and Young’s modulus, important characteristics of materials for prostheses. In case of elastic deformations of the bone—implant system, the load on the tissue depends on the ratio of the Young's modulus of the implant material and bone tissue. The lower this ratio, the lower the probability of necrosis and destruction of bone by implant pressure. Mechanical and biocompatibility increase the prospects for the introduction of materials developed by scientists in medicine, aerospace and defense industries.
"In implantation medicine, the Young's modulus of a metal implant, a value that characterizes the ability of a material to deform when force is applied, has to be artificially reduced in order to approximate the Young's modulus of bone tissue," explained Stepan Stepanov, Associate Professor of the UrFU Department of Heat Treatment and Metal Physics.
TNZTS alloy with a multi-element composition after intense plastic deformation showed stability of the structure and indicators of plasticity and Young's modulus. Niobium, zirconium, tantalum and tin have improved the mechanical properties of the material and increased its corrosion resistance, making this alloy suitable for medical applications.
The studied alloys differ from those used in medicine in several important aspects. Traditional medicine alloys contain metals with toxic properties such as aluminum and vanadium, while the studied materials contain niobium, zirconium, tantalum and tin, which are safer elements for the human body.
"Mechanically, the new alloys are more like bone tissue. Low values of the Young's modulus will reduce the risk of loosening of the implant in the surrounding tissues and improve its integration into the patient's bone. The ultra-fine-grained structure in the alloys, obtained as a result of intense plastic deformation, made them stronger than traditional low-modulus alloys, while ensuring a low Young's modulus. The new alloys have improved fatigue strength characteristics, which makes them more reliable for long-term use under cyclic loads typical of joints and other moving parts of the body," said Stepan Stepanov.
Before putting such alloys into practical use, scientists study their mechanical properties under various operating conditions in order to better understand the behavior of the material under loads and temperatures. It is also important for the medical field to evaluate the corrosion resistance of new alloys, as the materials will be exposed to biological environments. Before clinical trials, it will be necessary to optimize production and processing so that properties and quality remain stable during serial launch.
Widespread use will become possible after the development of standards and regulation for the use of alloys in specific industries.
Specialists from the Ural Federal University, Institute of Strength Physics and Materials Science SB RAS and National Research Tomsk Polytechnic University conducted the study.
Reference:
TNZ alloy is part of a broad group of titanium alloys that include other structural elements to improve biocompatibility and mechanical properties. Such alloys are already used in medicine, and their compositions are being investigated to obtain optimal characteristics.
TNZTS alloy is multicomponent system where the addition of tantalum and tin allows further stabilizing the alloy and improving its properties. Such modifications of the composition are aimed at improving mechanical properties without loss of biocompatibility.
The compositions of the studied alloys may include new proportions or combinations of elements, the main foundation for their development is based on already studied titanium alloy systems that have proven themselves well in medicine and dentistry.
Funding: The work was carried out with financial support under the Priority 300 program.
Published in journal: Materials Letters
Authors: A.Yu. Eroshenko, E.V. Legostaeva, P.V. Uvarkin, A.I. Tolmachev, M.A. Khimich, V.P. Kuznetsov, S.I. Stepanov, I.A. Vorontsov, G.Zh. Mukanov, Yu.P. Sharkeev
Source/Credit: Ural Federal University | Alexandra Khlopotova
Reference Number: ms021025_01
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