Strength enhancement and deformation behavior of gold after equal-channel angular pressing

The significant enhancement of strength is reported for pure K24 gold and its K18 alloys subjected to grain refinement by equal channel angular pressing (ECAP) in comparison with their annealed or ordinary cold-worked counterparts. The effect of strain path on the tensile behavior is discussed from the stand point of mechanical properties and damage evolution during straining. It is shown that although different processing can give rise to substantially different structures, the mechanical properties depend on the pre-strain history only slightly. The ECAP appears to be particularly effective for strengthening of pure gold and Au-Ag solid solutions where the strength can increase by a factor of 3 or 4 while in the precipitation hardenable alloys the effect of grain refinement is masked by other strengthening mechanisms and the strength increases by a factor of 2. The strain localization and features of plastic deformation in ECAP materials are discussed in detail upon in-situ and post-experimental surface observations in differently fabricated samples.