New experimental insight into the mechanisms of nanoplasticity

Abstract : The evolution of microstructure and texture of a nanocrystalline Pd-10 at.% Au alloy (initial grain size 16 nm) subjected to severe plastic deformation by high-pressure torsion (HPT) at room temperature is investigated by X-ray line profile analysis and X-ray microdiffraction, respectively. In addition, changes in the microhardness are measured and the texture is modeled. During HPT the microstructure changes: the crystallite size goes over the maximum, the dislocation density goes through a minimum and the density of stacking faults decreases at/up to a shear strain of similar to 1, corresponding to a grain size of 20 nm. Starting with a random texture, typical brass-type shear components develop at a shear strain above similar to 1. The microhardness with decreasing crystallite size goes over a maximum at nm. The correlated changes in microstructure, texture and strength strongly suggest the transition from a dislocation slip to a grain boundary sliding (GBS)-dominated deformation mechanism. The unexpected brass-type texture and its deviation from the ideal position can be simulated with the Taylor model assuming dominant partial dislocation slip and a certain contribution of GBS, respectively. Taken together, the results of many techniques applied to the same material, in particular those of the texture investigations, provide a more comprehensive and consistent picture of nanoplasticity than reported before for face-centered cubic metals.
Type de document :
Article dans une revue
Acta Materialia, Elsevier, 2013, 61 (19), pp.7271-7284. 〈10.1016/j.actamat.2013.08.032〉
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W. Skrotzki, A. Eschke, B. Joni, T. Ungar, Laszlo S. Toth, et al.. New experimental insight into the mechanisms of nanoplasticity. Acta Materialia, Elsevier, 2013, 61 (19), pp.7271-7284. 〈10.1016/j.actamat.2013.08.032〉. 〈hal-01501853〉



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