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Molecular dynamics simulations of strengthening due to silver precipitates in copper matrix
Author(s) -
Hocker Stephen,
Rapp Dennis,
Schmauder Siegfried
Publication year - 2017
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201600479
Subject(s) - materials science , dislocation , critical resolved shear stress , copper , shear (geology) , molecular dynamics , precipitation , crystallography , slip (aerodynamics) , condensed matter physics , shear stress , precipitation hardening , metallurgy , composite material , alloy , thermodynamics , chemistry , computational chemistry , physics , shear rate , meteorology , viscosity
Molecular dynamics simulations of edge dislocation interactions with coherent and incoherent silver precipitates in the copper matrix are applied to investigate precipitation strengthening. Simulated shear tests with spherical and octahedral precipitates revealed that dislocations can cut a precipitate or circumvent it by the Orowan mechanism. Precipitates with radii below 3 nm are cut whereas both processes were observed for radii in the range of 3–9 nm. The reason for the occurrence of the Orowan mechanism is that dislocation reactions at the interface can lead to sessile dislocations. Orowan circumvention is more likely for spheres than for octahedra which is due to different dislocation types existing at the matrix/precipitate interfaces. On average, the critical resolved shear stress is found to be slightly higher for Orowan processes. In case of small precipitates, the critical resolved shear stress depends strongly on the coherency, whereas for larger precipitates, it is mainly influenced by dislocation reactions at the interface. In some cases, the formation of a jog was observed which can reduce the critical resolved shear stress whereas it was increased significantly in the cases of pronounced cross‐slip without jog formation.