Comparison of the interaction behaviour of edge and screw dislocations with respect to precipitate interfaces

Dennis Rapp, Universität Stuttgart, Stuttgart, Germany

Using MD shear simulations, the edge/screw dislocation interaction with precipitates were investigated for the systems Ag-Cu and Cu-Ni-Si. For edge dislocations it could be shown that the regular interfaces of octahedral Ag-precipitates in Cu lead to cutting, whereas spherical precipitates exhibit Orowan circumvention. In contrast, screw dislocations with their ability to easily cross-slip have been found to completely circumvent the precipitate, i.e. the neither leave an Orowan loop behind nor cut through the precipitate. For the Cu-Ni-Si system two coherent precipitate types were investigated: the cylindrical δ-Ni2Si precipitate and the spherical β–Ni3Si precipitate. Edge dislocations cut through the spherical β-precipitates and Orowan circumvention only occurs at high coherency strains. For the δ-precipitates only one out of six orientations was found to favour cutting. Screw dislocations were found to circumvent the precipitates completely.

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Session M2: Moday, 25 June 2018

Start: 03:30 p.m.
End: 03:45 p.m