Performance analysis of Ti-Nb-Zr-Ta to development medium entropy alloys by powder metallurgy

The field of biomedical high entropy alloys has become a vital area because they can make human life easier. The most alloys used in biomedical application are Ti6Al4V due to the titanium element. Pure titanium (CP-Ti) has excellent corrosion resistance but the titanium and its alloys have high price [1, 2]. High Entropy Alloys (HEAs) are defined as alloys that consist of five main elements or more mixed in an equiatomic, near-equiatomic and equimasic fraction [3]. The behavior is being investigated for high entropy alloying elements and the design methods. Powder metallurgical techniques can be used to obtain HEA based on compatible alloy for biomedical applications with uncomplicated and inexpensive way to process. The demanded alloys for biomedical applications are excellent in plasticity, low in Young modulus, and high in strength; the alloy components are low-toxicity and are completely free from them. Many HEAs have superior mechanical properties, microstructure and good biocompatibility [4-7], in contrast to Ti6Al4V when used for bone implants; it has been shown that there is significant bone wear. Besides, aluminum and vanadium can have adverse effects on the human body [8]. In this work, a medium entropy alloys (MEA) base on Ti-Nb-Zr-Ta system (Ti25Nb25Zr25Ta25) has been studied using conventional powder metallurgy techniques. Their microstructure, mechanical properties and chemical properties have also been studied. The results obtained demonstrate the influence and performance of equiatomic and equimasic of these alloys and their ability to work successfully for possible use as biomedical implants

Effect of the Ti/Ta ratio on the feasibility of porous Ti25+x-Nb25-Zr25-Ta25-x (X= 0, 5, and 10) alloys for biomedical applications

Non-toxic biomedical HEAs by powder metallurgy methods have been scarcely studied despite their promising mechanical and biological behaviors. This work studied the microstructural, mechanical, electrochemical, and ion release effects of the Ti/Ta ratio on three porous Ti–Nb–Zr–Ta (TNZT) alloys. The microstructure of the TNZT alloys consisted of semi-equiaxed and micrometric BCC-phases (matrix) with lower contents of HCP phase. Elastic moduli (82–91 GPa), hardness (373–430 HVN), ultimate bending (225–475 MPa), and tensile (119–256 MPa) strength, electrochemical corrosion (4.5–9.6 μm year−1), and ion release (toxicity, 0.9–1.1 μm year−1) were within acceptable limits for implant biomaterials. Increasing the Ti content (and decreasing Ta) was advantageous for improving mechanical strengthening and reducing the elastic modulus. The medium value of elastic modulus may be beneficial to reduce the mechanical mismatch between the implant and the organic tissue. However, the corrosion rate and metallic ion release increased as a function of the Ti content. Besides, the alloy with the lowest Ti content (highest Ta content) showed local corrosion. Based on the above, the porous TNZT alloys with medium and highest Ti contents (30 and 35 wt%) were demonstrated as promising candidates for biomedical implant applications

The Effect of Ti/Ta Ratio and Processing Routes on the Hardness and Elastic Modulus of Porous TiNbZrTa Alloys

TiNbZrTa alloys are promising for multidisciplinary applications, such as refractory and biomedical purposes, due to their high thermal stability and non-toxicity. Hardness and elastic modulus are among the key features for their adequate industrial applications. The influence of porosity and Ti/Ta ratio were investigated on TiNbZrTa alloys produced by three different processing routes, i.e., (i) blend element and posterior press and sintering (BE + P&S); (ii) mechanical alloying with press and sintering (MA + P&S); and (iii) arc melting and casting. Porosity decreased in the following order: casting < MA + P&S < BE + P&S. The total porosity of alloys increased with increasing Ta contents, i.e., by lowering the Ti/Ta ratio. However, the Ti/Ta ratio did not considerably affect the bonding energy or the elastic modulus. Hardness was increased significantly in dense alloys compared to porous ones. However, porosity and Ti/Ta ratio did not show a clear trend in hardness among the porous alloys