In this work the mechanical properties and structural refinement in Cu-Sn and Cu-Zn solid solutions is studied after Severe Plastic Deformation (SPD). The mechanical properties like solid solution strengthening and strain rate sensitivity have been investigated in coarse grained state and after severe plastic deformation using both macroscopic and nanoindentation approaches. The strong indentation size effect (ISE) observed during indentation of the CG state shows pronounced work hardening. A combination of sequential polishing and high resolution EBSD measurements is used to determine the density of geometrically necessary dislocations. The ISE is then correlated with the dislocation density and the results are interpreted with respect to the contribution of solid solution strengthening effects of Sn and Zn.
Severe plastic deformation lead to a reduction in grain size and increase in strain rate sensitivity and the hardness of the solid solutions. Interestingly, in the ultra-fine-grained state, the strain rate sensitivity of the highest solute content alloy is the smallest, even though the material exhibits the smallest grain size. The mechanism leading to grain refinement in conjunction with dislocation mechanism at grain boundaries are discussed.
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