镁合金作为可降解生物材料，具有良好的生物相容性与力学相容性，但精密成形及降解过程控制难题限制了其临床应用。本项申请以Mg-Ca-X系合金为研究对象，以介入支架所用薄壁微管为载体，通过复合ECAP超细晶技术将微管成形与材料改性有机融合。以超细晶结构诱发的晶粒尺寸及晶界密度变化、合金相的再分布以及材料织构的变化为切入点，重点研究腐蚀类型、腐蚀速度、腐蚀均匀度等生物降解影响因子对于微结构变化的响应机制。并将支架在生物应力环境中的降解疲劳界定为力学失效与材料腐蚀的并行效应，通过生物模拟体液中的物理仿真辅以数值模拟，研究超细晶对于医用力学完整性失效的影响规律，探求医用力学参数和腐蚀参数在不同降解时段的对应规律及交互作用机制。以超细晶为驱动，在医用镁合金强塑性变形后发生超塑性、强韧化的基础上，探明其耐蚀化机制，揭示力-化并行作用下的生物降解控制原理，有助于建立体内外关联评价并寻求多种改性综合作用机制。

Magnesium alloys has significant advantages as potential degradable biomaterials for its excellent biocompatibility and appropriate mechanical properties. However, the difficulty to precise form and control the biodegradation process may limit its clinical applications. In this work, Mg-Ca-X alloy will be researched combined with the forming processes of micro-tube, which was used for implant stent. Ultra-fine grain strengthening will be investigated through integrated forming processes of hot equal channel angular pressing (ECAP) and multiple extrusion. The deformation of microtube and modification of material were also unithed in the processes. Micro-structural features and small compositional changes, such as grain size, grain boundary density, redistribution of inter-metallic phase and texture evolution, were researched. The influences of those factors upon the mechanical integrity fatigue were studied and the response of corrosion type, speed, uniformity and other factors affecting biodegradation were analyzed through physical simulation combined with numerical simulation in simulated body fluid. The degradation process of implant stent in biological stress environment was attributed to mechanical-chemical parallel effect of mechanical integrity fatigue and the corrosion of material. Corresponding rules and interaction mechanism between medical mechanical parameters and corrosion parameters in different degradation stage will be explored. To establish in vitro and in vivo correlated evaluation and to explore a variety of synthesis modification mechanism of Mg alloys as degradable biomaterials. Based on the super-plasticity, strengthening and toughening, the mechanism of enhanced corrosion resistance caused by multi-pass severe plastic deformation were demonstrated. The control principles of biodegradation caused by interaction effect of the mechanical properties and corrosion resistance were revealed.