晶粒细化对Cu-20Ag-30Cr合金在HCl溶液中腐蚀电化学行为的影响

采用机械合金化通过控制球磨时间制备不同晶粒尺寸的三元合金粉末,然后分别以真空热压工艺制备常规晶粒尺寸和纳米晶粒尺寸的Cu-20Ag-30Cr合金块状合金。并且利用PARM273A和M5210电化学综合测试系统对两种合金进行电化学腐蚀测试,通过测定电化学极化曲线和交流阻抗谱研究了常规晶粒尺寸和纳米晶粒尺寸的Cu-20Ag-30Cr合金在不同浓度HCl溶液中的腐蚀电化学行为。结果表明随着HCl浓度的增加,腐蚀电流密度随之持续增大,自腐蚀电位持续负移,传递电阻持续减小,表明合金的腐蚀程度加剧,合金的耐腐蚀性能减弱;在相同浓度的HCl溶液中,纳米晶粒尺寸的Cu-20Ag-30Cr合金的腐蚀电流密度明显高于高于Cu-20Ag-30Cr合金,表明经过晶粒细化合金腐蚀速度加快,其耐腐蚀性能下降。

Effect of grain size on corrosion electrochemical behavior of Cu-20Ag-30Cr alloy in HCl solution

Cu-20Ag-30Cr alloy powders with different grain size were prepared by mechanical alloying through controlling ball-milling time and afterwards coarse-grained and nanocrystalline bulk alloys were prepared by hot-pressing method.The corrosion electrochemical behavior of coarse-grained and nanocrystalline bulk Cu-20Ag-30Cr alloy in HCl solution were studied by means of PARM273A and M5210 electrochemical synthesis test system through potentiodynamic polarization method and electrochemical impedance spectroscopy （EIS） technique.Results show that the corrosion current densities of two alloys increase gradually,corrosion potentials move to the negative direction,and charge transfer resistance decrease gradually with the increase of HCl concentrations.The corrosion current densities of nanocrystalline Cu-20Ag-30Cr alloy increases and corrosion rates become fast as compared with the corresponding coarse—grained Cu-20Ag-30Cr alloy in HCl solution with the same concentrations.Thus,the corrosion resistances of Cu-20Ag-30Cr alloy fall off when the grain size is refined.