Nanostructured copper-silver alloys synthesized by high energy ball milling

High-energy ball milling has been used to synthesize nanostructured Cu-Ag alloys. Effect of nominal composition and milling temperature on the final steady-states has been studied. The synthesized powders have been systematically characterized by XRD, Nano-indentation, SEM, TEM, and for the first time, APFIM and 3D-AP analysis techniques.; Liquid Nitrogen temperature (LN2) milling leads to the stabilization of one fcc solid solution. The solid solution is nearly random, except for a weak long-range composition fluctuation, and the mixing takes place at atomic scale. Room temperature (315 K) milling also produce one single fcc solid solution, but with larger composition variations than the LN2 sample. It also shows that partial decomposition has already begun to take place at both large and small scales.; Nanocomposites can be synthesized by elevated temperature milling, with controlled length scale. 3D-AP analysis directly reveals the scales of decomposition: <2 nm for 393 K sample, <5 nm for 423 K samples, and <10 nm for 453 K samples.; Significant decomposition variations have also been observed in powders ball milled at intermediate temperatures. The inhomogeneous deformation process during the ball milling has been proposed to be the contributing factor to these variations. In general, the experimental results can be explained within the theoretical framework of driven systems, where the final steady state is a result of dynamic competition of thermally activated diffusion (which leads to decomposition), and repeated plastic deformation (which leads to mixing).; However, the large mutual solubility, diffused interface, and inhomogeneous structure, as observed in our experimental data, cannot be reproduced by computer simulations. This is probably due to the lack of deformation heterogeneities in current computer simulation models.; The synthesized nanostructured alloys also display high hardness values, in the range of 4–6 Gpa. The hardness increases as milling temperature increase, as a result of phase separation and dynamic recrystallization.