Materials Research Centre, School of Materials Science and Engineering, Zhengzhou University, Zhenzhou, 450002, PR China.
J Mech Behav Biomed Mater. 2012 Apr;8:1-7. doi: 10.1016/j.jmbbm.2011.12.011. Epub 2012 Jan 3.
Magnesium alloys are promising candidate materials for cardiovascular stents due to their good biocompatibility and degradation properties in the human body. However, in vivo tests also show that improvement in their mechanical properties and corrosion resistance is necessary before wide application. In this study, cyclic extrusion compression (CEC) was used to enhance the mechanical properties and corrosion resistance of Mg-Zn-Y-Nd alloy. The results show that the grain size was greatly refined to 1 μm after CEC treatment. The second phase distributed along the grain boundaries with grid shape and nano-sized particles uniformly distributed in grains. The elongation (δ), ultimate tensile strength (UTS) and yield strength (YS) of the CEC treatment samples were 30.2%, 303 MPa and 185 MPa respectively. The CEC treated samples showed homogeneous corrosion because of the grain refinement and the homogeneous distribution of nano-sized second phase. The corrosion current density of the alloy decreased from 2.8×10(-4) A/cm(2) to 6.6×10(-5) A/cm(2) after CEC treatment. Therefore, improved mechanical properties, uniform corrosion and reduced corrosion rate could be achieved by CEC.
镁合金由于其良好的生物相容性和在人体中的降解性能，是心血管支架的候选材料。然而，体内试验也表明，在广泛应用之前，需要提高其力学性能和耐腐蚀性。本研究采用循环挤压压缩（CEC）来提高 Mg-Zn-Y-Nd 合金的力学性能和耐腐蚀性。结果表明，CEC 处理后晶粒尺寸大大细化至 1 μm。第二相呈网格状分布于晶界，纳米级颗粒均匀分布于晶粒内。CEC 处理样品的伸长率（δ）、极限拉伸强度（UTS）和屈服强度（YS）分别为 30.2%、303 MPa 和 185 MPa。由于晶粒细化和纳米级第二相的均匀分布，CEC 处理样品表现出均匀腐蚀。合金的腐蚀电流密度从 2.8×10(-4) A/cm(2)降低到 6.6×10(-5) A/cm(2)。因此，CEC 可以提高力学性能、均匀腐蚀和降低腐蚀速率。
