Formation of cerium-based bulk metallic glasses

Abstract

We report the formation and composition range of Ce-based bulk metallic glasses. Ternary Ce–Al–Cu(Co,Ni) glassy rods of 1–3 mm in diameter can be easily formed in a wide composition range by a conventional copper mold cast method. Substituting Ce with low-cost Ce-rich misch metal (MM), MM–Al–Cu bulk glasses with a similar high glass-forming ability (GFA) can be obtained. With minor addition of extra elements such as Fe, Co, Ni, Nb, Zn and Si, the critical diameter of the full glassy rods of the Ce–Al–Cu matrix can be markedly enhanced from 2 mm to at least 3–10 mm. It is found that the often-cited empirical criteria for bulk metallic glass formation cannot interpret the formation and the addition effect on GFA of the metallic glasses. The striking effect and mechanism of microalloying on the GFA of the metallic glasses are studied. These materials with extremely low glass transition temperatures (341–439 K, even below the boiling temperature of water) and excellent deformability at low temperatures could have potential applications.