Modelling of strain rate dependent dislocation behavior of CNT/Al composites based on grain interior/grain boundary affected zone (GI/GBAZ)

摘要

The strain rate dislocation behavior in carbon nanotubes (CNTs) reinforcing aluminum is described through an explicit, analytic grain interior/grain boundary affected zone (GI/GBAZ) composite model. The model describes how the mechanical behavior of metal matrix composites, under different strain rates, depends on the different response of dislocation accommodation in GBAZ and GI which in turn origins from geometrically necessary dislocation (GNDs) and statistically stored dislocation (SSDs), respectively. An in-situ tracking of the strain rate dependent strain distribution and computational simulations were jointly employed to provide insight into the dislocation behavior. Given the different distributions of dislocations in the ultrafine grains of CNT/Al composites, mechanical response depends on how dislocations arrange in GI and GBAZ. Results from experiments and simulations, based on Crystal plasticity (CP) finite element modelling (FEM), clarified that the dominant deformation mechanism of the CNT/Al composite is strain rate dependent. The results show that the GI/GBAZ model can successfully reveal the dislocation dependency of strain rate. The results might shed some light on understanding of strain rate dependent dislocation behavior in metal matrix composites reinforced with nano-carbon structures such as CNTs.