A phase-field model is developed to simulate the corrosion of Mg alloys in body fluids. The model incorporates both Mg dissolution and the transport of Mg ions in solution, naturally predicting the transition from activation-controlled to diffusion-controlled bio-corrosion. In addition to uniform corrosion, the presented framework captures pitting corrosion and accounts for the synergistic effect of aggressive environments and mechanical loading in accelerating corrosion kinetics. The model applies to arbitrary 2D and 3D geometries with no special treatment for the evolution of the corrosion front, which is described using a diffuse interface approach. Experiments are conducted to validate the model and a good agreement is attained against in vitro measurements on Mg wires. The potential of the model to capture mechano-chemical effects during corrosion is demonstrated in case studies considering Mg wires in tension and bioabsorbable coronary Mg stents subjected to mechanical loading. The proposed methodology can be used to assess the in vitro and in vivo service life of Mg-based biomedical devices and optimize the design taking into account the effect of mechanical deformation on the corrosion rate. The model has the potential to advocate further development of Mg alloys as a biodegradable implant material for biomedical applications.
翻译:开发了一个相场模型,用于模拟镁合金在体液中的腐蚀。该模型结合了镁的溶解和镁离子在溶液中的传输,自然预测了从活化控制到扩散控制的生物腐蚀的转变。除了均匀腐蚀外,所提供的框架还捕捉了点蚀腐蚀,并考虑了侵蚀性环境和机械载荷在加速腐蚀动力学方面的协同效应。该模型适用于任意二维和三维几何形状,对于腐蚀前缘的演变不需要特殊处理,使用了一种模糊界面方法进行描述。进行了试验以验证该模型,并且在镁丝的体外测量方面达到了良好的一致性。在考虑了承受张力的镁丝和机械载荷作用下的可生物吸收的冠状镁支架的案例研究中,展示了该模型捕捉机-化效应的潜力。所提出的方法可以用于评估基于镁的生物医学设备的体外和体内使用寿命,并优化设计,考虑机械变形对腐蚀速率的影响。该模型具有进一步发展镁合金作为生物降解性植入材料的潜力。