Novel metallic systems and methods for their fabrication provide high temperature machine parts formed of a consolidated nano-crystalline metallic material. The material comprises a matrix formed of a solvent metal having a melting point greater than 1,250° C. with crystalline grains having diameters of no more than about 500 nm, and a plurality of dispersed metallic particles formed on the basis of a solute metal in the solvent metal matrix and having diameters of no more than about 200 nm. The particle density along the grain boundary of the matrix is as high as about 2 nm2 of grain boundary area per particle so as to substantially block grain boundary motion and rotation and limit creep at temperatures above 35% of the melting point of the consolidated nano-crystalline metallic material. The machine parts formed may include turbine blades, gears, hypersonics, radiation shielding, and other high temperature parts.