Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs
Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs
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DOI：
10.3390/ma8052467
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发表时间：
2015-05-08
期刊：
影响因子：
3.4
通讯作者：
Mitevski B
中科院分区：
文献类型：
--
作者：
Weiss S;Mitevski B
冠心病仍然是西方工业国家最常见的死亡原因之一。自1986年以来，已经插入金属血管支架（支架）以防止血管壁塌陷。这些冠状动脉支架大多由CrNiMo合金钢（316L）制成。由于其奥氏体结构，该材料显示出强度、延展性、耐腐蚀性和生物相容性的良好组合。然而，这种材料具有一些缺点，如其非MRI兼容性和其较差的荧光透视可见性。其他常用的材料是钴基合金L-605和F-562，它们与MRI兼容且不透射线。另一个有趣的事实是它们出色的径向强度，因此能够生产具有更高强度的超薄支柱。然而，由于支柱直径远小于100 μ m，横截面由约5至10个晶粒组成（寡聚结晶）。因此，很少或甚至仅仅一个颗粒可以负责整个支架的成功或失败。为了研究微观结构、机械因素与支架设计之间的关系，对市售钴铬合金支架进行了研究，重点关注由于压握和扩张引起的明显不均匀塑性变形。确定了一种特征性的材料相关变形行为（主要是初次滑动）是CoCr支架特殊性能的原因。
Coronary heart disease is still one of the most common sources for death in western industrial countries. Since 1986, a metal vessel scaffold (stent) has been inserted to prevent the vessel wall from collapsing. Most of these coronary stents are made from CrNiMosteel (316L). Due to its austenitic structure, the material shows a good combination of strength, ductility, corrosion resistance, and biocompatibility. However, this material has some disadvantages like its non-MRI compatibility and its poor fluoroscopic visibility. Other typically used materials are the CoBase alloys L-605 and F-562 which are MRI compatible as well as radiopaque. Another interesting fact is their excellent radial strength and therefore the ability to produce extra thin struts with increased strength. However, because of a strut diameter much less than 100 μm, the cross section consists of about 5 to 10 crystal grains (oligocrystalline). Thus, very few or even just one grain can be responsible for the success or failure of the whole stent. To investigate the relation between microstructure, mechanical factors and stent design, commercially available Cobalt-Chromium stents were investigated with focus on distinct inhomogeneous plastic deformation due to crimping and dilation. A characteristic, material related deformation behavior with predominantly primary slip was identified to be responsible for the special properties of CoCr stents.