A bimodal microstructure for fatigue resistant metals by molecular dynamics simulations

We propose a new bimodal microstructure with promising potential for developing fatigue-resistant metals taking advantage of molecular dynamics (MD) simulations. In the proposed bimodal microstructure, each micrometer-sized grain is separated by a network of ultrafine nanocrystalline structure. Then, MD simulations of low cycle fatigue deformation of the proposed bimodal microstructure were performed. Modeling results suggest that most of the dislocations generated by the repeated plastic deformation (or the low cycle fatigue) are absorbed by the nanocrystalline network. No significant accumulation of dislocations is observed within the micrograins. This work suggests a potential path to achieve high fatigue resistance in metals as compared with their microcrystalline counterparts, which would be useful in nearly every engineering setting.