Direct evidence of nanocrystal enhanced complete mutual solubility in mechanically alloyed CoCu powders

A continuous series of CoxCu(100−x) solid solutions have been fabricated by mechanical alloying. Transmission electron microscopy observations found that there are three kinds of particle morphology with lamellar, irregular and spherical shapes and their corresponding energy dispersion X-ray spectroscopic analyses (EDAX) values are quite different; the larger the crystallite size, the lower the content of cobalt. The greatly enhanced mutual solubility in Co and Cu powders during mechanical alloying may be caused by Co atoms substituting Cu atoms in the grain boundaries and vice versa, and by the large increase in the diffusion coefficient between Co and Cu atoms induced by the structural defects and local stresses in the nanocrystals.