Co-Cu alloys produced by mechanical alloying of powder precursors characterized by different contact surface and energy excess

Abstract

Co-Cu alloys were prepared by mechanical alloying using different reaction mixtures (mechanical mixture of Co and Cu powders, composite powders (Co(100 − y)P(y))100 − x/Cux with a crystalline core, and composite powders (Co(100 − y)P(y))100 − x/Cux with an amorphous core). The use of a complex of structural and magnetostructural methods showed that these alloys are nonuniform nanocomposite materials consisting of two phases, namely, copper- and cobalt-based solid solutions. During the mechanical alloying of the composite powders, parameters that are sensitive to the short-range-order structure of both phases were found to be changed, namely, the lattice parameter in the Cu-based solid solution as determined from X-ray diffraction patterns, and the Bloch constant that is sensitive to the short-range order in the Co-based solid solution change. In the alloys prepared by mechanical alloying of composite powders with an amorphous core, the lattice parameter a and the Bloch constant B reach values corresponding to metastable Co100 − xCux solid solutions in milling times of 1.5–2.0 h. These times are lower by 1–2 orders of magnitude than the typical times that are necessary for forming metastable Co-Cu solid solutions by standard methods of mechanical alloying from mixtures of powders.