Development of biodegradable Mg-Ca alloy sheets with enhanced strength and corrosion properties through the refinement and uniform dispersion of the Mg₂Ca phase by high-ratio differential speed rolling.
Development of biodegradable Mg-Ca alloy sheets with enhanced strength and corrosion properties through the refinement and uniform dispersion of the Mg₂Ca phase by high-ratio differential speed rolling.
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DOI：
10.1016/j.actbio.2014.09.029
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发表时间：
2015
影响因子：
9.7
通讯作者：
J. Seong;W. J. Kim
中科院分区：
文献类型：
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作者：
J. Seong;W. J. Kim
提出了一种制备高Ca含量（2-3 wt.%）可生物降解Mg-Ca二元合金的新工艺通过调整其微观结构而具有增强的抗生物腐蚀性的片材形式。采用挤压-大差速轧制（HRDSR）和轧后退火工艺对Mg-Ca合金中的Mg 2Ca相进行了有效的细化和分散，形成了均匀的显微组织，其中亚微米和纳米尺寸的Mg 2Ca颗粒分布在晶粒尺寸为1.6 μm的细晶再结晶基体上。Mg 2Ca相破碎成细小且孤立的颗粒以及它们在基体中的均匀分散大大降低了基体和Mg 2Ca相之间的单独微电偶腐蚀的敏感性，并且变形后退火降低了位错密度，同时由于存在通过抑制再结晶中的晶界运动而减小晶粒尺寸的细小分散的Mg 2Ca颗粒而形成小晶粒，导致Mg-Ca合金在Hank溶液中的耐腐蚀性的显著改善。与纯镁相比，经退火HRDSR处理的Mg-Ca合金具有更高的耐腐蚀性和更高的机械强度。本研究提出的工艺路线为生产具有良好强度和耐腐蚀性能的可生物降解镁合金板材提供了新的机会。
A novel processing route was proposed for the fabrication of biodegradable Mg–Ca binary alloys with high Ca contents (2–3 wt.%) in sheet form with enhanced biocorrosion resistance by tailoring their microstructures. The effective refinement and dispersion of the Mg2Ca phase in the Mg–Ca alloys using extrusion followed by high-ratio differential speed rolling (HRDSR) and post-rolling annealing led to the formation of homogeneous microstructures in which submicron-sized and nanosized Mg2Ca particles were distributed over the fine-grained recrystallized matrices with grain sizes of ∼6 μm. The break-up of the Mg2Ca phase into fine and isolated particles and their uniform dispersion in the matrix greatly decreased the susceptibility of individual microgalvanic corrosion between the matrix and Mg2Ca phase and the post-deformation annealing decreased the dislocation density while forming small grains due to the presence of the finely dispersed Mg2Ca particles that reduced the grain sizes by inhibiting grain boundary motion in recrystallization, resulting in a significant improvement in the corrosion resistance of Mg–Ca alloys in Hank’s solution. The annealed HRDSR-processed Mg–Ca alloys showed higher corrosion resistance and higher mechanical strength compared with pure magnesium. The processing routes proposed in this study provide a new opportunity for the production of biodegradable magnesium alloy sheets with good strength and corrosion properties.