Stochastic Effect of Fracture Toughness and Toughening Mechanism on Nanocrsyalline materials Size Variants Produced by Accumulative Roll-Bonding (ARB)

Abstract

The current studies focus on the varying approaches of measuring nanomaterial’s fracture toughness and toughening mechanism during grain refinement by accumulative roll bonding. It is very difficult to compare and correlation results of nanomaterial mechanical properties. This is due to the varying top down and bottom up approaches of manufacturing nanomaterials. There are other problem due to varying means of defining strain, varying means of imposing strain on the material and varying mathematical equation used in modeling. The tool of stochastic mechanics and fracture mechanics were used to model the physical activity that takes place during ARB process. The following facts were experimentally revealed and validated. It was revealed that varying directions of measuring grain sizes have varying effects on yield stress and fracture. It was also shown that grain boundaries with higher grain curvatures have more enhanced fracture toughness and cracks propagation is lower. The varying fracture toughness on nanomaterial’s size variants were due to varying grain size curvature and grain orientation during deformation.