In this talk an overview of the room temperature grain coarsening effect in polymer-supported thin gold and copper films under cyclic mechanical loading will be presented. Detailed EBSD analysis, as the major characterization method, allows to capture extensive statistical data about the evolution of thousands of grains with the cycle number but also to observe the motion and elimination of single grain boundaries. It will be shown that very strong and homogeneous grain coarsening occurs in 500 nm gold films where the average grain size grows from 200 nm to approximately 2 µm during cyclic loading. In contrast, 500 nm thick copper films with bi-modal grain size distribution exhibit rather moderate grain coarsening which leads to the reduction of the fraction of ultra-fine grained areas. The correlation between the grain coarsening and the development of fatigue damage will be discussed along with background mechanisms of motion and elimination of grain boundaries.
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