【摘要】 采用电弧熔炼(CA)和机械合金化(MA)通过热压烧结工艺制备了晶粒尺寸差别较大的Cu-40Ni合金,借助于PARM273A和M5210电化学综合测量仪,利用动电位扫描法和交流阻抗技术对比研究了上述合金在酸性含Cl-介质中的腐蚀电化学性能以及腐蚀机制。结果表明:两种合金的腐蚀电位随时间逐渐稳定,在中性Na2SO4溶液中加入H2SO4和NaCl后,两种合金的自腐蚀电位负移;晶粒细化后,两种合金的自腐蚀电位则正移。两种合金在中性及酸性含Cl-介质中均存在钝化现象,但在酸性含Cl-介质中钝化区间很短,钝化能力较弱。两种合金的交流阻抗谱均由单容抗弧组成,反应由电化学过程控制。晶粒细化后,合金中存在大量晶界,参与腐蚀反应的活性原子数增加,促使MACu-40Ni合金的腐蚀速度高于CACu-40Ni合金。更多还原

【Abstract】 Corrosion mechanism and corrosion-resistances of Cu-40Ni alloys prepared by conventional casting（CA）,mechanical alloy and hot-pressing processes（MA） with the great different grain size in acidic media containing Cl^-were investigated by PARM273A and M5210 electrochemical apparatus through potentiodynamic polarization method and electrochemical impedance spectroscopy（EIS） technique.Results show that the corrosion potential of CACu-40Ni and MACu-40Ni alloys moves negatively when adding H₂SO₄ and NaCl to Na₂SO₄ solution,while the corrosion potential of the two alloys moves positively with the reduction of the grain size.There is passive phenomenon in potentiodynamic polarization curves for the two alloys in Na₂SO₄ media and acidic media containing Cl^-,but range of passivation is very narrow in acidic media containing Cl^-.Corrosion current increases,so corrosion resistance decreases for the two alloys with adding H₂SO₄ and NaCl to Na₂SO₄ solution and the reduction of the grain size.The electrochemical impedance spectroscopy（EIS） of the two alloys in acidic media containing Cl^-is composed of single capacitive loop,therefore corrosion process is controlled by electrochemical reaction.The corrosion rate of MACu-40Ni alloy becomes faster than that of CACu-40Ni alloy because the reduction in the grain size of MACu-40Ni alloy produces large concentrations of grain boundaries and increases the number of reactive atoms over alloy surface.更多还原