Electrocatalytic Mapping of Metal Fatigue with Persistent Slip Bands.

Metal fatigue, characterized by the accumulation of dislocation defects, is a prevalent failure mode in structural materials. Nondestructive early-stage detection of metal fatigue is extremely important to prevent disastrous events and protect human life. However, the lack of a precise quantitative method to visualize fatigue with spatiotemporal resolution poses a significant obstacle to timely detection. Here, we demonstrate a nondestructive electrocatalytic method to visualize metal fatigue, which is promising for future fatigue early detections. The persistent slip band (PSB) is considered one of the most consequential defect structures for metal fatigue failure. The selective electrochemistry is highly dependent on the metal crystallography and the collective dislocations in the PSB structure, enabling the amplification of the electrochemical response and differentiation of the fatigue stages at a submillimeter resolution. In addition, this nondestructive electrocatalytic method is applicable to several common metals, including copper, silver, iron, and aluminum, holding great significance where metal fatigue is a critical concern.