Mg61Cu28Gd11和(Mg0.61Cu0.28Gd0.11)99.5Sb0.5非晶合金的晶化动力学和腐蚀行为

摘要

0.5% (molar fraction) Sb was added to Mg61Cu28Gd11 glass forming alloy to improve its thermal stability and corrosion resistance. The crystallization kinetics of Mg61Cu28Gd11 and (Mg0.61Cu0.28Gd0.11)99.5Sb0.5 amorphous alloys was investigated under continuous heating. The temperatures of glass transition,onset and peak crystallization for the two glasses exhibit strong heating-rate dependence. The activation energies for the onset and peak crystallization were determined based on the Oawza plots.Vogel-Fulcher-Tamman equation analysis shows that the larger strength parameter and much longer relaxation time are obtained due to the Sb addition. The corrosion properties of the two glassy alloys were studied by means of potentiodynamic and immersion tests.Compared with the parent alloy,(Mg0.61Cu0.28Gd0.11)99.5Sb0.5 glassy alloy exhibits a superior corrosion resistance in Cl--containing alkaline solution,as indicated by the lower passive current density and corrosion rate. Based on the point defect model,the effect mechanism of Sb addition on corrosion resistance of Mg-Cu-Gd glassy alloy is carefully identified.%研究0.5%(摩尔分数)Sb的引入对Mg61Cu28Gd11块体非晶合金性能的影响.利用差热扫描量热仪测试样品的晶化动力学.结果表明:在等时加热的过程中,非晶合金的玻璃转变温度、起始晶化和峰值晶化温度都表现出对加热速率强的依赖性.基于Oawza方法可以确定非晶合金的起始晶化和峰值晶化激活能.Vogel-Fulcher-Tamman公式分析表明:含Sb元素的非晶合金具有更高的强度系数和更长的延迟时间.采用电化学极化和失重测试方法研究2种玻璃合金的腐蚀行为.与基体非晶合金相比,添加微量Sb降低了非晶合金的在含Cl-的碱性溶液中的钝化电流密度和腐蚀速率,表现出相比基体合金更为优越的耐蚀性.最后基于"点缺陷模型"进一步分析微量Sb元素对基体合金耐蚀性能的影响机理.