Primary and Secondary Dealloying of Au(Pt)-Ag: Structural and Compositional Evolutions, and Volume Shrinkage
Primary and Secondary Dealloying of Au(Pt)-Ag: Structural and Compositional Evolutions, and Volume Shrinkage
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DOI：
10.1149/2.0131412jes
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发表时间：
2014
影响因子：
3.9
通讯作者：
X. Ye;Ning Lu;Xiaojie Li;K. Du;J. Tan;H. Jin
中科院分区：
文献类型：
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作者：
X. Ye;Ning Lu;Xiaojie Li;K. Du;J. Tan;H. Jin
对Au-Ag和Au（Pt）-Ag合金的脱合金化的系统研究表明，脱合金化通过两个过程发生：一个主要的脱合金化过程，其选择性地从母合金中溶解Ag并产生纳米多孔（np）结构，以及一个二次脱合金化过程，其发生在腐蚀前沿之后并进一步溶解来自纳米韧带的残余Ag。二次去合金化可以发生在粗化过程中，和/或当施加更阳极化的电势时。随着含Pt样品中np结构粗化的抑制，我们发现由初级去合金化产生的本征np结构包含小的韧带直径（3-7 nm）和高浓度的残余Ag（类似于50 at.%），而与去合金化电位无关。膨胀实验表明，一次脱合金时的体积收缩较小，二次脱合金时的体积收缩较大。初生脱合金可用渗滤溶解机制解释。虽然二次脱合金化（无粗化）的机制尚不清楚，我们指出，二次脱合金化的动力学是决定性的一些重要特征的np金属，如裂纹的形成和最终残留的Ag浓度。(c)2014年电化学学会。All rights reserved.
Systematic study of the dealloying of Au-Ag and Au(Pt)-Ag alloys shows that the dealloying occurs by two processes: a primary dealloying process that selectively dissolves Ag from the parent alloy and creates a nanoporous (np) structure, and a secondary dealloying process that occurs behind the corrosion front and further dissolves the residual Ag from the nano-ligaments. The secondary dealloying can occur during coarsening, and/or when a more anodic potential is applied. With suppressed np structure coarsening in Pt-containing samples, we found that the intrinsic np structure created by the primary dealloying contains small ligament diameter (3-7 nm) and high concentration of residual Ag (similar to 50 at.%), irrespective of the dealloying potentials. Dilatometry experiments show that the volume shrinkages are rather small during primary dealloying and are large during secondary dealloying. The primary dealloying can be explained by the percolation dissolution mechanism. Although the mechanism of the secondary dealloying (without coarsening) remains unclear, we point out that the kinetics of the secondary dealloying is decisive to some important characters of np metals, such as the crack formation and the final residual Ag concentrations. (c) 2014 The Electrochemical Society. All rights reserved.