Bulk nano-crystalline alloys FeYB and CuZrAl by direct casting

Bulk nano-crystalline alloys (BNCAs), at least 1 mm in diameter, were obtained in Fe–Y–B and Cu–Zr–Al ternary alloys by direct casting with average nano-crystallite sizes 10 nm and 25 nm, respectively. It was found that composition (glass-forming-elements, GFEs) and cast-size are major roles determining the ability of casting into BNCAs. A ‘dynamic continuous-cooling-crystallization (CCC)’ model was proposed, in which the CCC-curve keeps shifting rightward during nano-crystallization and cooling-down, thus amorphous matrix can be restored. Upon formation of nano-crystals, the GFE is ejected out and piled up at surrounding amorphous matrix to keep the nano-crystals from growth.