Deformation Processed Metal-Metal Composites

Abstract

Deformation processed metal–metal composites (DMMCs) are composites in which both the matrix and the reinforcing phase are ductile metals. The ductility of the metals permits the composite to be heavily deformed by drawing or rolling to reduce the thickness and spacing of the two phases to as small as 10 nm. Their nano‐scale microstructures are exceptionally strong, with strengths approaching whisker strength in some cases. And since the materials are comprised of two essentially pure metals, their electrical conductivities are quite high for current flow in directions parallel to the composite’s filaments or lamellae, leading to numerous potential applications. During the 1990s, continuing research has produced DMMCs in a wide range of matrix metals, including Al, Au, Mg, Sc, and Ti. Methods are also being developed to produce DMMCs with much larger dimensions in rod and sheet forms to permit their use in a wider variety of engineering applications.

A deformation-processed Al-matrix/Ca-nanofilamentary composite with low density, high strength, and high conductivity

“…Conventional strengthening methods such as strain hardening, second-phase hardening, precipitate hardening, or solid solution hardening significantly decrease conductivity. A type of composite called deformation processed metalmetal composites (DMMCs) has been found to exceed the rule-of-mixtures strength prediction and also deliver an electrical conductivity nearly equal to the rule-of-mixtures prediction [2].…”

“…DMMCs are essentially nano-scale bundles of two pure metals whose unique microstructure provides minimal electron scattering effect (along the filament direction) from solute impurities, interfaces, grain boundaries, or dislocations [4]. Though many DMMC systems have been studied in the past few decades [2], none possess densities and electrical conductivities close to those of pure Al. Al/Ca DMMCs were invented [5] to produce a light, highly conductive, high-strength composite conductor.…”

“…The light gray Ca filaments adopted a ribbon-shaped morphology instead of the expected cylindrical shape. According to the classic composite morphology theory [2,12], in a fcc matrix DMMC, a bcc metal filament tends to develop a <110> fiber texture parallel to the deformation axis, which leads to a plain strain deformation mode that would form a ribbon-like curling filamentary morphology. In contrast, fcc filaments tend to deform axisymmetrically to develop a cylindrical filament morphology due to the larger number of slip planes available in a textured fcc matrix.…”

Nanostructured Multifilamentary Carbon‐Copper Composites: Fabrication, Microstructural Characterization, and Properties

“…It consists of a series of steps involving first co-drawing of bimetallic monofilamentary macrocomposite, bundling and restacking of the drawn elements followed by another drawing operation. Accumulative drawing and re-stacking result in to multifilamentary materials with a priori incompatible properties, such a high yield strength and good electrical conductivity [29,30]. The archetypes of these materials are the Cu-Nb micro-or nanocomposites, used to manufacture coils generating very high magnetic fields [31,32].…”

Rich Tomography Techniques for the Analysis of Microstructure and Deformation

“…The behavior of these materials differs from conventional matrix composites in that both matrix and reinforcing phase are ductile metals [Russell et al (2000)]. Typically, metal-metal composites are manufactured using co-spay forming methods [ Kelly et al (2011)], and may involve blending together a face centered cubic (fcc) metal with a body centered cubic (bcc) metal, e.g., Cu-Nb or Al-Nb, or an fcc metal with a hexagonal close-packed (hcp) metal, e.g., Al-Ti.…”