Highly porous Ni-free Ti-based scaffolds with large recoverable strain for biomedical applications

Abstract

Highly porous Ti-18Zr-12.5Nb-25n (at.%) scaffolds with porosities of 70%, 75% and 80% were prepared by sintering rapidly solidified alloy fibers. Superelastic behavior of alloy fiber was investigated by the dynamic mechanical analyzer (DMA). Phase identifications of alloy fiber and scaffold were studied by X-ray diffraction (XRD). Precipitates in alloy fiber were investigated by transmission electron microscope (TEM). Porous structure of alloy scaffold was observed by scanning electron microscope (SEM). Mechanical properties and the superelasticity of alloy scaffold were investigated using compressive test. The superelasticity of alloy fibers was improved after aged at 673 K for 3.6 ks due to alpha precipitates. The sintered scaffolds showed three-dimensional networks with fiber-fiber sintering joints. The compressive yield stress and elastic modulus of the alloy scaffolds aged at 673 K for 3.6 ks were in the range of 5.0-16.7 MPa and 0.33-1.05 GPa, respectively. These values were a close match to those for cancellous bone. The recoverable strain increased from 3.2% to 3.7% with the increase in porosity from 70% to 80% in aged Ti-Zr-Nb-Sn scaffolds when tested at human body temperature (310 K).