A preparation and optical property study of Nanostructured-Metal Materials

气相脱合金（VPD）有望成为一种通用、高效、环保的制备三维双连续纳米多孔金属的方法，该方法利用组成元素之间的蒸汽压差。然而，由于潜在的脱合金动力学，如组成元素的热蒸发，导致块状合金和孔道中的扩散，以及合金的相演变，脱合金条件与上述显微组织参数之间的关系仍然不清楚。本文选择Cu12Zn88合金的气相脱合金（VPD）作为模型体系，研究了其脱合金动力学和合金相演化过程。我们发现，在VPD过程中，由于Cu和Zn之间的蒸气压差，Zn选择性地从Cu12Zn88合金的前驱体中蒸发出来，并且在Zn蒸发之前在合金化前形成中间相Cu36Zn64。孔隙深度与脱溶时间的幂律关系揭示了中间相的体扩散控制脱溶过程。多孔结构在中间区域开始出现，其出现时间与合金化温度密切相关。恒定的脱合金前沿速度主要受脱合金温度的影响，在高真空条件下略有增加，说明脱合金动力学主要受孔隙通道内的界面效应而非传质效应的影响。

Vapor phase dealloying (VPD) is expected as a universal, highly efficient and environmentally friendly method for fabricating 3D bicontinuous nanoporous metals, by using vapor pressure difference between constituent elements. However, the relation between dealloying conditions and above microstructural parameters are still unclear due to underlying dealloying kinetics, such as thermal evaporation of constituent element, resulting diffusion both in bulk alloys and in pore channels, and alloys phase evolution. In this work, 3D bicontinuous nanoporous Cu by vapor phase dealloying (VPD) of Cu12Zn88 alloy is chosen as the model system and its dealloying kinetics and alloy phase evolution are investigated. We found that Zn is selectively evaporated out from the precursor Cu12Zn88 alloy during the process of VPD due to the vapor pressure difference between Cu and Zn and an intermediate phase Cu36Zn64 is formed in the dealloying front before Zn evaporation. The power law relation between the pore depth and dealloying time reveals the bulk diffusion controlled dealloying process for intermediate phase. The porous structure starts to appear in the intermediate region and the appearance time closely relies on dealloying temperature. The constant dealloying front velocity is mainly dominated by dealloying temperature and slightly increased in high vacuum condition, indicating that the dealloying kinetics is dominated by interfacial effect rather than mass transport effect in pore channel.