微量Sr、Sn对Mg-Zn-Ca-Mn合金力学和腐蚀性能的影响

目的研究Sr、Sn元素对快速凝固制备的Mg ZnCaMn合金室温力学性能和生物腐蚀性能的影响规律。方法采用X射线衍射仪、扫描电子显微镜、差热分析仪、万能力学实验机、静态浸泡、电化学测试等实验手段,分别研究添加Sr/Sn元素对MgZnCaMn合金结构、微观组织变化、热学性能、室温强度、塑性变形及体外降解行为的影响。结果添加Sr元素后,MgZnCaMn合金中的非晶相数量增加,尤其是Mg64.7Zn30Ca4Mn0.8Sr0.5合金浸泡析氢量显著降低,自腐蚀电流密度为1.61×10~(-4)A/cm~2,平均腐蚀速率为0.35 mm/a,抗压强度为621MPa,塑性压缩应变为0.8%。添加Sn元素后,MgZnCaMn合金中的非晶相近乎完全消失,合金组织中主要为雪花状的Mg2Sn相及MnZn13相,合金的析氢量无显著变化,其与Mg65.2Zn30Ca4Mn0.8合金的自腐蚀电流密度皆在10~(-4)数量级,其抗压强度为412 MPa,压缩塑性应变为1.6%。结论添加Sr元素可以提高MgZnCaMn合金的非晶形成能力,增加非晶相体积分数,同时提升了合金的强度和腐蚀性能。添加Sn元素则降低了MgZnCaMn合金的非晶形成能力,合金主要由延性相构成,其室温塑性得到明显改善,与初始合金相比,耐蚀性略有降低,但仍然优于常规的生物医用镁合金(如高纯镁、Mg-Zn-Ca等),具有较好的耐蚀性。

Effect of Trace Sr and Sn on Mechanical and Corrosion Properties of Mg-Zn-Ca-Mn Alloy

The work aims to study the effect of Sr/Sn on the mechanical and bio-corrosion properties of rapidly solidified MgZnCaMn alloys. The effects of Sr/Sn on the structure, microstructure, thermal properties, room temperature strength, plastic deformation and in vitro degradation of MgZnCaMn alloys were investigated by X-ray diffraction, scanning electron microscopy, differential thermal analysis, universal capacity test machine, static immersion and electrochemical testing, respectively. After the addition of Sr element, the amount of amorphous phase in MgZnCaMn alloy increased, and the amount of hydrogen evolution in Mg64.7Zn30Ca4Mn0.8Sr0.5 alloy decreased significantly. The self-corrosion current density was 1.61×10?4 A/cm2, the average corrosion rate was 0.35 mm/a, the compressive strength was 621 MPa and the plastic compressive strain was 0.8%. After the addition of Sn element, the amorphous phase in the MgZnCaMn alloy disappeared almost completely. The snow-like Mg2Sn phase and MnZn13 phase were the main phases in the alloy. The hydrogen evolution of the alloy had no significant change. The self-corrosion current density were at magnitude of 10?4, the compressive strength was 412 MPa, and the compressive plastic strain was 1.6%. The addition of Sr can improve the amorphous forming ability of MgZnCaMn alloy, increase the volume fraction of amorphous phase, and improve the strength and corrosion performance of the alloy. The addition of Sn element reduces the amorphous forming ability of MgZnCaMn alloy. The alloy is mainly composed of ductile phase, and its room temperature plasticity is obviously improved. Compared with the initial alloy, the corrosion resistance reduces slightly, but it is still superior to conventional biomedical magnesium. Alloys (such as high-purity magnesium Mg, Mg-Zn-Ca, etc.) have good corrosion resistance.