Film-Induced Cleavage of Ag-Au Alloys
Film-Induced Cleavage of Ag-Au Alloys
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DOI：
10.1007/s11661-008-9714-z
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发表时间：
2009-01-01
影响因子：
2.8
通讯作者：
Newman, Roger C.
中科院分区：
文献类型：
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作者：
Barnes, Andrew;Senior, Nicholas A.;Newman, Roger C.
在去合金化环境（高氯酸）中对Ag-20进行了单次断裂实验。pct Au和Ag-23 at. pct Au合金分别以细线和箔的形式。这种环境会在表面产生纳米多孔金属层。穿晶断裂促进在一些线实验诱导竹晶粒结构。使用线，它表明，可以获得完整的脆性晶间或穿晶断裂，通过在脱合金过程中施加非常低的拉伸应力，通过脱合金后无应力快速应变的线，或通过应变后，第一次下降的电位到一个值，其中很少或没有进一步的法拉第反应是可能的失败。发现极低的断裂应力，特别是沿晶断裂，并且所有断裂事件都是突然的，没有二次基体断裂。箔的工作表明，在丝的响应中注意到的一些不可再现性与脱合金层的过早自断裂有关。通过优化脱合金层的条件，获得了可重复性极高且完整的膜诱导断裂。这些脱合金层显示出以前没有见过的特性，例如即使在去离子水中浸泡5分钟后也能注入深的基底裂纹。最近的研究表明，脱合金层具有非凡的机械性能，例如接近理论的压缩强度，这使得这种仍然神秘的断裂机制更加可信。详细反驳的替代“表面流动性”模型的索赔。
Single-shot fracture experiments have been carried out in a dealloying environment (perchloric acid) on Ag-20 at. pct Au and Ag-23 at. pct Au alloys in the form of thin wire and foil, respectively. Such environments produce a nanoporous metallic layer on the surface. Transgranular fracture was promoted in some of the wire experiments by inducing a bamboo grain structure. Using the wires, it was shown that complete brittle intergranular or transgranular fracture could be obtained, either by applying a very low tensile stress during dealloying, by rapidly straining the wire after dealloying without stress, or by straining to failure after first dropping the potential to a value where little or no further faradaic reaction was possible. Extremely low fracture stresses were found, especially for intergranular fracture, and all fracture events were sudden with no secondary substrate fracture. The work with foils showed that some irreproducibility noted in the response of the wires was associated with premature self-fracture of the dealloyed layer. By optimizing the condition of the dealloyed layer, extremely reproducible and complete film-induced fractures were obtained. These dealloyed layers showed properties not previously seen, such as an ability to inject deep substrate cracks even after a 5-minute immersion in deionized water. Recent studies showing extraordinary mechanical properties of dealloyed layers, such as near-theoretical strength in compression, give more credibility to this still-mysterious fracture mechanism. A detailed rebuttal of the claims of the alternative "surface mobility'' model is presented.