模拟体液环境下植入用Ti6Al7Nb合金的高周疲劳行为

On the High Cycle Fatigue Behavior of Implant Ti6Al7Nb Alloy in Simulated Body Fluid

Ti6Al7Nb合金作为一种新型的医用植入材料,在临床上已得到了推广应用,其在人体内长期服役情况下的疲劳行为值得关注。本文采用超声加速振动疲劳实验结合扫描电子显微镜微观观察,研究了植入用Ti6Al7Nb合金在空气和模拟体液环境下的高周疲劳行为。结果显示,Ti6Al7Nb合金不存在传统意义上的疲劳极限,其疲劳强度随着循环周次的增大而减小;Ti6Al7Nb合金在模拟体液环境中的疲劳性能远低于空气环境中,在108周次下的疲劳强度比空气环境中低23%;Ti6Al7Nb合金在空气和模拟体液中的疲劳性能都低于Ti6Al4V合金。断口显微观察发现,疲劳裂纹均萌生于试样表面。模拟体液会导致材料脆化,促进表面疲劳裂纹的萌生,从而降低材料的疲劳强度。

As a new type of implanted medical material, Ti6Al7Nb alloy has been popularized and applied in clinical practice, and its fatigue behavior in long-term service in human body deserves more attention. In this paper, high cycle fatigue behavior of implanted medical Ti6Al7Nb alloy in both air and simulated body fluid environments was studied by means of ultrasonic accelerated vibration fatigue experiment and microscopic observation of scanning electron microscope. Results demonstrate that Ti6Al7Nb alloy does not have conventional fatigue limit, and its fatigue strength decreases with the increase of cycle times. The fatigue strength of Ti6Al7Nb alloy in simulated body fluid environment is much lower than that in air. Its fatigue strength in simulated body fluid environment at 108 cycles is lower than that in air environment up to 23 %. The fatigue performance of Ti6Al7Nb alloy in both air and simulated body fluid environments are lower than that of Ti6A14V alloy. Microscopic observation of fracture surface reveals that all faigue cracks initiate on sample surface. Simulated body fluid may lead to the material embrittlement and promote the initiation of fatigue crack, which reduces material fatigue strength.