Characterization of multicomponent beta titanium alloys with low elastic modulus

Abstract

The use of Ti-6Al-4V alloy as biomaterial is more convenient among Ti alloys due to its large scale production for aeronautical applications worldwide. But it is well known that Ti-6Al-4V alloy may be detrimental to the patient's health (due to Al and V toxicity) and does not have the most suitable properties. The increase in the life expectancy makes necessary the scientific and technological development of the metallic biomaterials, mainly those with application in orthopedics. The metallic alloys currently used in Brazil have much greater elastic modulus (E) than that of human bone (E = 10 to 30 GPa), such as: stainless steel (200 GPa), Co-Cr alloys (220 GPa), Ti-6Al-4V (110 GPa) and the search for new alloys with better mechanical and chemical biocompatibility is required. The b-Ti alloys (bcc) present the best mechanical biocompatibility (elastic modulus, in the range of E = 55 to 80 GPa) and chemical (better corrosion resistance, cell adhesion and osseointegration). Although more expensive by the addition of noble elements to Ti, the implant itself is not the most expensive in a surgery, and when we treat the patient's health, the price of the material should not be a point of discussion, but rather always the best material possible. In the present project, high-entropy (HEA) multicomponent ²-Ti equimassic alloys (same weight%) Ti-25Nb-25Zr-25Ta, Ti-20Nb-20Zr-20Ta-20Mo (wt.%) are proposed as well as Ti-Zr-Nb alloys with high fractions of Zr and based on electronic parameters Bo and Md seeking the lowest elastic modulus (between 40 and 50 GPa). b-Ti alloys with different fractions of b-stabilizing elements will be compared, and possibly forming different combinations of phases (b, a", w, a' e a) in the resulting microstructure. A more favorable combination of microstructure and properties will be sought, aiming reduced elastic modulus E (GPa).The objective of this work is to characterize the new high-entropy (HEA) multicomponent ²-Ti equimassic alloys (same weight%) and Ti-Nb-Zr alloys system with respective influence of ²-stabilizer elements on the microstructure and properties, such as the rigidity, E (GPa), for furnace arc melt alloys.