MD-based characterization of plastic deformation in Cu/Ag nanocomposites via dislocation extraction analysis: Effects of nanosized surface porosities and voids
A Kardani and A Montazeri, COMPUTATIONAL MATERIALS SCIENCE, 152, 381-392 (2018).
Recently, copper-silver nanocomposites (NCs) have been utilized in medical instruments owing to their ability in destroying the bacterial cell wall, which prevents inflammation of the body tissue. It has been revealed that introducing nanosized porosities in their structure can lead to an increase in the interfacial surface area with the tissue promoting the quality of treatment. However, since yielding and occurrence of plastic deformation are not acceptable in medicine, analyzing the mechanical behavior of these NCs having nanopores is an important challenge. Therefore, the focus of this study is to assess the role of porosities on the deformation mechanism of Cu/Ag NCs under uniaxial tensile loading conditions. Accordingly, several perfect and defected samples are systematically studied through molecular dynamics simulation. It is observed that plastic deformation of perfect sample occurs through twinning. For samples with surface voids, this is happened as a result of perfect dislocations gliding. Meanwhile, for volumetric porosities, the deteriorating effect is stopped passing the critical void content. This is ascribed to the formation of many motionless dislocations such as stair-rod, Hirth and Frank as confirmed via the dislocation extraction analysis. Consequently, it is demonstrated that presence of surface voids can be more destructive.
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