Abstract:
Titanium and Ti based alloys drawn significant attention than conventional counterparts
(CoCr Mo, 316L SS) as orthopedic implant application due to suitable mechanical
properties and sufficient chemical stability in physiological body environment. In the
present study, b-type high entropy alloy MoNbTaTiZr with varying concentration of filler
element was designed by thermo calc software and developed by arc melting route. 3D
inter-connected porosity with porosity range (4.1,8.7,14 & 18%) was introduced with
removal of filler element by novel chemical dealloying method. XRD and SEM results
confirmed the formation of dual BCC microstructure. The elastic modulus and mechanical
strength of implant are successfully optimized by synergetic effect of high entropy alloys
and porosity. The elastic modulus tailored between (42- 3.5) GPa and yield strength
between (803- 108.5) MPa respectively. The microhardness values are higher than bone.
Interconnected open cell 3d porous structure enhance surface roughness, surface area and
hydrophilicity thus enhance bioactivity. Metallic implants surface was alkali treated to
enhance surface energy then coated with hydroxyapatite by biomimetic method to
enhance bioactivity. Corrosion studies of high entropy foams were carried out in simulated
body fluid at body physiological conditions. The developed foams show higher corrosion
resistance and electrochemical stability, required for biomedical applications. Overall
developed high entropy foams consist of biocompatible elements, shows superior
mechanical properties then conventional materials used and are best suited material for
orthopedic implants.
