Vapor phase dealloying kinetics of MnZn alloys
Vapor phase dealloying kinetics of MnZn alloys
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DOI：
10.1016/j.actamat.2021.116916
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发表时间：
2021-05-08
期刊：
影响因子：
9.4
通讯作者：
Chen, Mingwei
中科院分区：
文献类型：
--
作者：
Lu, Zhen;Zhang, Fan;Chen, Mingwei
气相脱合金（VPD）是一种环保的制备纳米多孔材料的方法，它利用元素的饱和蒸汽压差来选择性地驱动合金中一种或多种成分的升华。VPD动力学尚未被探索，复杂纳米结构内固气转化的速率控制因素仍然未知。以锰锌合金为原型系统，系统地研究了温度和压力对脱合金速度的影响，并建立了定量描述脱合金动力学的模型。结果表明，在一定的脱合金深度，脱合金速度呈线性向幂律转变，这是脱合金的动力学过程和微观组织相互作用的结果。这种转变将早期的弹道蒸发与Zn蒸气在发育的孔道中的Knudsen扩散连接起来，在此孔道中，合金化前沿的Zn分压达到固相和气相之间的局部平衡。通过比较VPD和体锌升华的活化能，测量了VPD的整个能量格局。对VPD动力学的基本理解为设计可脱合金前驱体合金和优化VPD材料的脱合金微观结构铺平了有效途径，为广泛的应用奠定了基础。(c) 2021 Acta Materialia Inc.Elsevier Ltd.出版。版权所有。
Vapor phase dealloying (VPD) is an environmentally-friendly method for fabricating nanoporous materials by utilizing the saturated vapor pressure difference of elements to selectively drive sublimation of one or more components from an alloy. VPD kinetics has not been explored and rate-controlling factors of the solid-gas transformation within complex nanostructure remain unknown. Using manganese-zinc alloys as a prototype system, we systematically investigated the dependence of dealloying velocity on temperature and pressure and presented a model to quantitatively describe the dealloying kinetics. We found that the dealloying velocity exhibits a linear to power law transition at a critical dealloying depth, resulting from the interplay between the kinetic process of dealloying and dealloyed microstructure. This transition bridges ballistic evaporation at early time to Knudsen diffusion of Zn vapor in developed pore channels where the Zn partial pressure at the dealloying front reaches the local equilibrium between the solid and vapor phases. By comparing activation energies for VPD and bulk zinc sublimation, the entire energy landscape of VPD is measured. The fundamental understanding of VPD kinetics paves an effective way to design dealloyable precursor alloys and to optimize dealloyed microstructure of VPD materials for a wide range of applications.(c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.