Acid assisted cold welding and intermetallic formation

A metallic composite solid, containing alloys and/or intermetallics, is formed by compacting at moderate pressure a mixture of powder particles, foils or sheets at a temperature close to room temperature, well below the melting temperature of the constituent components and without the addition of low melting metals such as mercury, indium or gallium acting as a sintering agent. This low temperature consolidation of the powder mixture is enhanced by having the surface oxide of the powder particles removed, prior to consolidation, and/or by coating the particles with an oxide-replacing metal such as silver or gold. The coating process may be replacement reactions, autocatalytic reduction or electrolytic reduction. The composite formation is assisted by the addition of a liquid acid such as fluoroboric acid, sulfuric acid, fluoric acid, adipic acid, ascorbic acid, or nitric acid. A preferred embodiment of the process for metal solid composite formation is a process for forming dental restorative materials at ambient temperatures and under pressure exerted by manual dental instrumentation.