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WEB A novel bimodal microstructure for improved fatigue resistance in metals

Tuesday (22.09.2020)
17:35 - 17:50 S: Structural Materials 1
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The talk will present a new bimodal microstructure for improving metal fatigue using molecular dynamics (MD) modeling. In this bimodal microstructure, individual micrometer-sized grains are completely separated by a network of ultrafine nanocrystalline structure. MD simulations of low cycle fatigue deformation of the proposed bimodal microstructure suggest that most of the dislocations generated by the repeated plastic deformation are absorbed by the nanocrystalline network. No significant accumulation of dislocations is observed within the micrograins. This indicates that the formation of crack initiation is largely hindered in the bimodal microstructure. The underlying mechanism is probably related to the intrinsic characteristic of nanograin boundaries. The excess volume (or the width) of nanograin boundaries in the nanocrystalline network changes reversely during the repeated compression and tension, impacting the dislocation behavior within micrograins. This work suggests a potential path to achieve high fatigue resistance in metals as compared with their microcrystalline counterparts.

Dr. Wenwu Xu
San Diego State University