Intergranular stress-corrosion cracking (IGSCC) is a form of environmentally induced crack propagation causing premature failure of elemental metals and alloys. It is believed to require the simultaneous presence of tensile stress and corrosion; however, the exact nature of this synergy has eluded experimental identification. For noble metal alloys such as Ag–Au, IGSCC is a consequence of dealloying corrosion, forming a nanoporous gold layer that is believed to have the ability to transmit cracks into grain boundaries in un-dealloyed parent phase via a pure mechanical process. Here using atomic-scale techniques and statistical characterizations for this alloy system, we show that the separate roles of stress and anodic dissolution can be decoupled and that the apparent synergy exists owing to rapid time-dependent morphology changes at the dealloyed layer/parent phase interface. We discuss the applicability of our findings to the IGSCC of important engineering Fe- and Ni-based alloys in critical applications.

晶间应力腐蚀开裂（IGSCC）是一种环境引起的裂纹扩展，导致元素金属和合金过早失效。据认为需要同时存在拉应力和腐蚀。但是，这种协同作用的确切性质尚无法进行实验鉴定。对于Ag-Au之类的贵金属合金，IGSCC是脱合金腐蚀的结果，形成了纳米孔金层，该层被认为具有通过纯机械工艺将裂纹传递到未脱合金母相中的晶界的能力。在这里，使用原子级技术和该合金系统的统计表征，我们表明，应力和阳极溶解的单独作用可以分离，并且由于脱合金层/母相界面的快速随时间变化的形态变化而存在明显的协同作用。我们讨论了我们的发现在重要应用中对重要工程铁和镍基合金在IGSCC中的适用性。