铁镁非平衡合金人工骨的机械合金化与选区激光熔化制备机理研究

可降解金属如铁、镁、锌等在骨植入物领域被寄予厚望，不足之处在于铁降解速率过慢，而镁、锌等作为合金元素固溶于铁基体中能降低电极电位从而加快降解；但它们属于难互溶体系，常规方法难以使其形成固溶体。本研究旨在利用机械合金化的非平衡性和强制性突破相图极限，获得过饱和固溶体的难互溶合金粉末，再利用选区激光熔化升温速率快和作用时间短的特点避免合金元素从固溶体中析出，制备非平衡合金人工骨。在机械合金化过程中，拟揭示难互溶合金体系中原子扩散过程和过饱和固溶体形成原因及反应机理；查明合金粉末物相组成、颗粒形貌、尺寸和分布的关键影响因素；并优化机械合金化工艺参数。在选区激光熔化过程中，研究成型工艺参数对合金组织结构、成分以及致密化的影响；分析成形过程中微观结构演变过程和调控机理。探明人工骨中过饱和相的形成机制及其对相关力学与生物学性能的影响；并优化选区激光熔化工艺参数，为实现降解速率可控的非平衡合金人工骨的制备提供理论支撑。

Biodegradable metals, such as iron, magnesium and zinc, etc., are highly expected in the field of bone implants, while the defect is the too slow degradation rate of iron. Fortunately, magnesium, zinc, etc. can reduce the electrode potential of the alloy and so to improve the degradation performance when it is dissolved in the iron matrix as an alloying element. However, they are difficult miscibility system so it is hard to form homogeneous alloy by regular means. Therefore, this study aims to break through the limitation of phase diagram by utilizing the non-equilibrium and coerciveness of mechanical alloying, getting the immiscible alloy powders of supersaturated solid solution. And then to prepare the non-equilibrium alloy artificial bone utilizing the rapid heating rate and short action time feature of the selective laser melting to avoid the precipitation of alloying elements from the solid solution. In the process of mechanical alloying, we intend to reveal the atomic diffusion process in the immiscible alloy system and the formation reason and reaction mechanism of supersaturated solid solution and find out the key factors of phase composition, particle morphology, size and distribution of alloy powders. Besides, the process parameters of mechanical alloying are to be optimized. What's more, during selective laser sintering, the effects of molding parameters on microstructure, composition and densification of the alloy are studied and the evolution and regulation mechanism of microstructure while forming are analyzed. In addition, the evolution mechanism of supersaturated phase in artificial bone and its influence on relevant mechanical and biological properties are explored. Except from that, the laser melting process parameters are optimized. Those works provide theoretical support for the preparation of non-equilibrium alloy artificial bone with controllable degradation rate.