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为开发生物医用镁合金,利用高纯原材料,在氩气气氛保护下熔炼浇铸制备了Ca合金化的Mg-4Zn合金(Ca含量分别为0.4%和1.0%,质量分数)。通过OM、SEM以及XRD分析了合金的微观组织和相组成,采用析氢法、腐蚀质量损失法以及电化学法测试了合金在Hanks模拟体液中的腐蚀行为。结果表明,合金由初生Mg固溶体和共晶体组成;随Ca含量增加,合金的电荷传递电阻减小,自腐蚀电位下降,自腐蚀电流密度增加;析氢法和腐蚀质量损失法均表明合金的腐蚀速率随时间延长而减小。共晶体对合金的耐蚀性有影响;当Ca含量从0.4%增加到1.0%时,共晶体含量增加,促进了合金的电偶腐蚀,合金耐蚀性降低。Mg-4Zn-(0.4,1)Ca合金的腐蚀形式主要为晶间腐蚀和点蚀。
In order to develop bio-medical magnesium alloy, Ca alloyed Mg-4Zn alloy (0.4% and 1.0% Ca, respectively) was prepared by melting and casting high purity raw materials under argon atmosphere. The microstructure and phase composition of the alloy were analyzed by OM, SEM and XRD. The corrosion behavior of the alloy in simulated body fluids of Hanks was tested by hydrogen evolution method, corrosion mass loss method and electrochemical method. The results show that the alloy consists of primary Mg solid solution and eutectic. With the increase of Ca content, the charge transfer resistance of the alloy decreases, the self-corrosion potential decreases and the self-corrosion current density increases. Both the hydrogen evolution method and the corrosion mass loss method show that the alloy corrosion rate Decrease with time. When the content of Ca increased from 0.4% to 1.0%, the eutectic content increased, which promoted the galvanic corrosion of the alloy and the corrosion resistance of the alloy decreased. The corrosion forms of Mg-4Zn- (0.4,1) Ca alloy are mainly intergranular corrosion and pitting corrosion.