Deformation-induced nanoscale mixing reactions in Cu/Ni and Ag/Pd multilayers

Abstract

During the repeated cold rolling of Cu/Ni and Ag/Pd multilayers, a solid solution forms at the interfaces as nanoscale layer structure with a composition that replicates the overall multilayer composition. The interfacial mixing behavior was investigated by means of X-ray diffraction and scanning transmission electron microscopy. During deformation induced reaction, the intermixing behavior of the Cu/Ni and Ag/Pd multilayers is in contrast to thermally activated diffusion behavior. This distinct behavior can provide new kinetic pathways and offer opportunities for microstructure control that cannot be achieved by thermal processing.

Mixing behaviors in Cu/Ni and Ni/V multilayers induced by cold rolling

“…The composition profile between two end members does not vary smoothly and continuously, but shows a compositional oscillation. This interesting behavior has also been observed in our previous EELS investigation [8]. The compositional oscillation is not expected in the composition profile due to thermally activated diffusion [9][10][11] thus it is a unique behavior induced by deformation.…”

Interfacial mixing of nickel vanadium multilayers induced by cold rolling

“…The composition profile for a Cu/Nb multilayer after accumulative roll bonding and subsequent high pressure torsion was found to have an oscillation shape between the end members [43]. In previous work [6,8], the composition profile of Cu-Ni multilayer after cold rolling was found to be oscillating in the mixing zone between pure Cu and Ni. The above investigations on intermixing behavior induced by mechanical alloying indicate that although the solid solutions were eventually achieved as a consequence of external deformation, the kinetics vary among different systems.…”

“…For example, in our previous investigation of Cu/Ni multilayers subjected to cold rolling [6,8], the solid solution peak in the XRD pattern appears at the position that corresponds to the solid solution with a nominal composition, i.e. Cu 60 Ni 40 .…”

“…The unique capability of MA is exemplified by several novel structures such as the extension of solid solubility in systems that are immiscible in equilibrium [2][3][4], the synthesis of metallic glass [5] and different kinetic pathways in solid solution formation [6]. These novel structures are not initiated by the usual thermally activated diffusion.…”

“…On the other hand, the repeated cold rolling of multilayers allows for the detailed examination of interface reactions at each stage of deformation so that a clear measure can be obtained between the extent of interfacial atomic scale mixing and the input of deformation work. In a prior work, the extent and character of the interfacial mixing was examined during deformation of multilayers in the isomorphous Cu-Ni system [6,8]. As a next step in the systematic study of deformation induced interfacial reactions, the Ni-V system was selected since the end members have different crystal structures and there are several intermediate alloy phases.…”