Microstructure and Properties of Porous Medical Titanium Alloy Implanted in Bones with Different Mo Contents AITranslate

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Basic Information:

DOI：10.13373/j.cnki.cjrm.XY24010037

Chinese Library Classification Number:TG135

Citation Information:

With the development of human biomedical level，requirements for medical materials have been enhanced. It requires high mechanical properties and outstanding corrosion resistance，etc. Titanium and titanium alloys are widely utilized in the fields of shipbuilding，aerospace，biomedical and chemical industries because of high specific strengths and good fatigue properties，low elastic modulus，excellent bio-compatibility and great corrosion resistance. However，the elastic modulus of titanium alloys that have been implanted into the host bone as a load-bearing material is much higher than that of host bones. It results in insufficient bearing of the host bones which triggers off the phenomenon of "stress shielding" and the atrophy and resorption of host bones. Eventually，it will lead to the failure of operation and implantation. Thereby，to solve the problem of mismatch of mechanical properties caused by elastic modulus of titanium alloy，researchers have carried out a variety of studies on the descent of elastic modulus of titanium alloy. It is mainly employed in accordance with such two aspects. Firstly，the design optimization of porous structures in titanium alloys. The introduction of pore structure could significantly reduce the elastic modulus of titanium alloys，and the connected porous structure with appropriate pore sizes was conducive to fluid exchange and the adhesion，proliferation and differentiation of osteoblasts on the surfaces of alloys. Consequently，new bone tissues that grow into pores would strengthen the connection between titanium alloys and bone，which would further improve the biocompatibility of titanium alloys. Additionally，the addition of β stabilizer could take an advantage of low elastic modulus of β-Ti，which promoted the development of a novel titanium alloy. As a β stabilizer，Mo can not only dramatically stabilize β phase，improve the mechanical properties of the alloys，but also improve the corrosion resistance of titanium alloys. However，most of the current studies focued on the influence of Mo on the microstructure and mechanical properties of dense titanium alloys. Meanwhile，there were few studies on the microstructure，mechanical properties and corrosion resistance of porous Ti-Mo alloys. As a consequence，pore structures，microstructures，mechanical properties and corrosion resistances of porous Ti-Mo alloys prepared by powder metallurgy were studied by multi-scale characterization methods such as optical microscopy （OM），scanning electron microscopy （SEM）and X-ray diffraction （XRD）in this research. Firstly，the complete porous Ti-Mo alloy samples were prepared by ball milling，cold pressing，desalination and sintering of Ti and Mo powders，and then the pore structures of porous Ti-Mo alloys were determined by Archimedes drainage methods and line intercept methods. The results demonstrated that with the increase of Mo element content from 5 at% to 20 at%，the number of tiny Kirkendall pores distributed on the skeleton of porous Ti-Mo alloys soared，the porosity of porous Ti-Mo alloys increased slightly from 38.06% to 41.36%，and the pore sizes were enhanced from 289.34 to 323.11 µm. Meanwhile，the microstructure characterization illustrated that the porous Ti-Mo alloys were mainly composed of α phase and β phase，the volume fraction of the α phase gradually plunged and the volume fraction of the β phase gradually ascended with the increase of Mo element contents. The α phase within grains gradually transformed from lamellae to needle-like shape and eventually disappeared. The ultimate compressive strength and elastic modulus of the porous Ti-Mo alloys gradually decreased as the content of Mo increased from 5 at% to 20 at% at room temperature. Finally，the results of corrosion resistance demonstrated that the self-corrosion potential increased from -281.8 to -225.8 mV and then decreased to-287.7 mV，and Ti-10Mo alloys exhibited better corrosion resistances.