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采用粉末冶金模压烧结技术制备了Ti-(2~20)Fe二元合金,探讨了Fe含量对合金的力学性能及耐腐蚀性能的影响,并与铸造CP Ti和Ti-6Al-4V合金的耐腐蚀性能进行了对比。结果表明,随着Fe含量的增加,合金α相含量逐渐降低,β相含量逐渐提高。当Fe含量达到20%时,基本形成单一β相合金。随Fe含量的升高,粉末冶金Ti-(2~20)Fe二元合金的强度及塑性趋于升高,而弹性模量趋于降低。相对而言,Ti-15Fe合金的综合性能最佳,其抗压强度为2702 MPa,压缩率为32.7%,弹性模量为64.6 GPa。随着Fe含量在2%~15%范围内提高,合金的自腐蚀电位正向移动,腐蚀电流密度降低,极化电阻不断增大,腐蚀速率不断降低,耐蚀性能逐渐提高,而Ti-20Fe合金耐腐蚀性能与Ti-15Fe合金接近。Ti-15Fe合金在模拟口腔液(FAS)、磷酸盐缓冲溶液(PBS)、模拟体液(SBF)以及0.9%NaCl溶液(SS)中的腐蚀速率分别为1.7×10^-3、7.1×10^-4、1.2×10^-3和3.5×10^-4 mm/y。与铸造CP Ti和Ti-6Al-4V合金相比,Ti-15Fe合金具有较正的自腐蚀电位、较小的腐蚀电流密度和腐蚀速率及较大的极化电阻,耐蚀性能明显优于CP Ti和Ti-6Al-4V合金。

Titanium and its alloys have been widely used in the biomedical field, and have a great potential in making orthopedic implants due to their high specific strength, low elastic modulus, excellent biocompatibility and corrosion resistance in the human body environment. However, important titanium alloys currently used including extra low interstitial (ELI) Ti-6Al-4V (hereafter all in mass fraction, %), Ti-5Al-2.5Fe and Ti-6Al-7Nb are all at risk of releasing toxic Al and V ions in vivo. In addition, the elastic modulus (about 110 GPa) of these alloys are still much higher than those of cortical bones (about 20 GPa), which may bring severe ‘stress shielding’ for implantation failures. In order to solve these problems, much effort has been made to develop Al- and V-free lower-modulus β-Ti alloys. Considering that Fe is one of most effective and low-cost β-phase stabilizing element in titanium, binary Ti-Fe alloys have been selected and an assessment of the potential for biomedical applications has been conducted from the perspectives of their manufacturability, mechanical properties and biocorrosion performance. In this study, Ti-xFe (2%≤x≤20%) alloys were fabricated by powder metallurgy, and their microstructure and compression properties were characterized. In particular, the corrosion properties in four different simulated physiological electrolytes at (37±0.5) ℃ were investigated according to ASTM 59-97, compared with the performances of two commonly used titanium-based materials Ti-6Al-4V and commercially pure (CP) titanium. The results show that the content of β phase gradually increases with Fe content increasing. When Fe content goes up to 20%, the alloy samples are only composed of single β-phase grains. The PM-fabricated Ti-(2~20)Fe alloy is provided with a superior combination of mechanical properties, with the compressive strength range of 2096.2~2702.3 MPa, the compression ratio of 20.6%~33.2% and the elasticity modulus of 62.7~85.5 GPa. Higher Fe content tends to lead to the higher strength and ductility, but lower elastic modulus. In comparison, Ti-15Fe sintered at 1150 ℃ exhibits the superior mechanical properties, including the elastic modulus of 64.6 GPa, the compressive strength of 2702 MPa, and the compression rate of 32.7%. With the rise of Fe content in 2%~15%, the corrosion potential of alloys moves to a positive position, and the corrosion current density decreases, corresponding to the increase in the polarization resistance, which suggests the improvement of their corrosion properties. The binary alloy with 20%Fe possesses the similar corrosion performance to that of Ti-15Fe. The corrosion rates of Ti-15Fe alloy in simulated oral solution (FAS), phosphate buffer solution (PBS), simulated body fluid solution (SBF) and 0.9%NaCl solution (SS) are 1.7×10^-3, 7.1×10^-4, 1.2×10^-3 and 3.5×10^-4 mm/y, respectively. Compared with CP Ti and Ti-6Al-4V, Ti-15Fe alloy exhibits a more positive corrosion potential, smaller corrosion current density and higher polarization resistance, indicating a superior corrosion resistance.