Ni_(74.7)Au_(25.3)合金在1mol/L HNO_3中的去合金化

Study of Dealloying Ni_(74.7)Au_(25.3) in 1 mol/L HNO_3 Solution

研究了Ni74.7Au25.3铸态合金在1 mol/L HNO3中的电化学行为和去合金化后的表面形貌.结果表明:Ni74.7Au25.3铸态合金具有通过不连续析出获得的富Au和富Ni两相组织;在极化曲线中活化区,Ni74.7Au25.3合金的腐蚀电流密度低于Ni的腐蚀电流密度.合金在1 mol/L HNO3中阳极极化和恒电位腐蚀后均可出现纳米孔隙组织,只是合金中两相组织仅富Ni相发生Ni的选择性溶解,形成纳米孔隙形貌;而富Au相没有变化.由此获得微米量级的复相组织,一相为致密的富Au相,另一相为具有纳米孔隙的纯Au相.

The electrochemical behavior and the surface morphology after dealloying of as-cast Ni74.7Au25.3 alloy in 1 moL/L HNO3 solution were investigated. The results indicate that as-cast Ni74.7Au25.3 alloy is consist of Au-rich and Ni-rich binary phases by discontinuous precipitation, and the current density of Ni74.7 Au25.3 alloy in active region of the polarization curve is lower than that of pure Ni. The nanoporous morphology can be obtained only in the Ni-rich phase of the alloy by dealloying in 1 moL/L HNO3 solution, and the Au-rich phase does not undergo the selective corrosion, resulted in the formation of compound microstructure in micro scale with dense Au-rich phase and pure Au phase with nanoporous structure.