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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 medical implant material, Ti6Al7Nb alloy has been popularized clinically and its fatigue behavior under long-term service in the human body deserves attention. In this paper, ultrasonic accelerated vibration fatigue test combined with the scanning electron microscope microscopic observation of Ti6Al7Nb implanted Ti alloy in air and simulated body fluid environment high cycle fatigue behavior. The results show that there is no traditional fatigue limit of Ti6Al7Nb alloy, and the fatigue strength of Ti6Al7Nb alloy decreases with the increase of cycle number. The fatigue performance of Ti6Al7Nb alloy in simulated body fluid environment is much lower than that in air environment. Under the fatigue strength of 23% lower than the air environment; Ti6Al7Nb alloy in air and simulated body fluid fatigue properties are lower than the Ti6Al4V alloy. Fracture microscopic observation found that fatigue cracks were sprouted on the specimen surface. Simulating body fluids can lead to embrittlement of materials and promote the initiation of surface fatigue cracks, thereby reducing the fatigue strength of the material.