Slip band formation in low and high solute aluminum: a combined experimental and modeling study
A Prakash and TN Tak and NN Pai and SVSN Murty and PJ Guruprasad and RD Doherty and I Samajdar, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 29, 085016 (2021).
Direct ex situ observations related slip band formation with deformed microstructures in commercial AA1050 and AA2219. The samples from both grades had similar grain sizes (similar to 250 mu m) and nearly random crystallographic textures. However, AA2219 contained significantly more solute. Slip bands, on the internal long transverse (LT) plane in split channel die specimens, were characterized by primary spacings (lambda) of 2-9 mu m, heights (Z) of 160-360 nm and secondary shear strains (gamma(S)(LT)). Higher deformation temperatures for both grades increased A, decreased, Z and reduced gamma(S)(LT). At all deformation temperatures, AA1050 had smaller lambda and higher Z, while AA2219 showed higher gamma(S)(LT). Ingrain misorientations, but not residual strains, were larger in grains with finer lambda in AA1050, but less so in AA2219. Discrete dislocation dynamics (DDD) simulations reported realistic slip bands with slip localizations. The simulations, initiated with static obstacles and sources, led to dislocation interactions and junction formation. The probability of junction stabilization (p) determined the ratio of dynamic sources to obstacles. Slip band formation appeared to be an outcome of the release of piled up dislocations leading to dislocation avalanches. Slip localization increased weakly with finer active slip plane spacing (lambda*), giving higher dynamic obstacle strengths and densities, but strongly with smaller p. In particular, the DDD simulations captured experimental patterns of higher slip localizations and dislocation densities in low solute aluminum with finer lambda*.
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