Effect of rapid quenching and severe plastic deformation on silver

Pure silver has been rapidly quenched (RQ) in ribbon form by means of planar flow casting with different cooling rates, obtained with different velocities of the cooling wheel. Ingots of pure silver have been subjected to severe plastic deformation (SPD) using constrained groove pressing and equal-channel angular pressing. The grain size of RQ and SPD samples has been analysed using electron microscopy, showing that the higher the solidification rate and plastic deformation, the finer the microstructure. Preferred orientations and quenched-in defect concentration have been determined from X-ray diffraction analysis, showing a correlation between density of defects and cooling rate. Higher defect concentration was found in the samples processed via SPD. Vickers hardness numbers range from 135 for SPD, 70 for RQ and 45 for annealed samples. Differential scanning calorimetry analysis revealed multi-step coarsening of the microstructure at various temperatures for all samples.