A binary or higher order high-density thermodynamically stable nanostructured copper-tantalum based metallic system according to embodiments of the invention may be formed of: a solvent of copper (Cu) metal that comprises 70 to 100 atomic percent (at. %) of the metallic system; and a solute of tantalum (Ta) metal dispersed in the solvent metal, that comprises 0.01 to 15 at. % of the metallic system. The metallic system is thermally stable, with the absence of substantial gross grain growth, such that the internal grain size of the solvent metal is substantially suppressed to no more than about 250 nm at approximately 98% of the melting point temperature of the solvent metal and the solute metal remains substantially uniformly dispersed in the solvent metal at that temperature. Processes for forming these metallic systems may include: subjecting powder metals of solvent and the solute to a high-energy milling process using a high-energy milling device to impart high impact energies to its contents. Due to their high-density thermodynamically stable nanostructured, these metallic systems are an ideal candidate for fabricating shaped charge liners for ordinance.