EFFECT OF COEXISTENCE OF SIMILAR ELEMENTS La AND Ce ON FORMATION OF (La-Ce)-Al-Cu BULK METALLIC GLASSES

摘要

Bulk metallic glasses (BMGs) in pseudo-ternary (La-Ce)-Al-Cu system with high glass-forming ability (GFA) were synthesized based on the beneficial effect of the coexistence of similar elements La and Ce with similar atomic size and various valence electronic structures on GFA. With the coexistence of La and Ce in (La_xCe1-x)65Al10Cu25 system, bulk metallic glasses with diameters up to 12 mm can be produced by copper mold casting. Besides the high GFA, the (LaxCe1-x)65Al10Cu25 BMGs with x = 0.6 and 0.7 exhibit low glass transition temperature Tg around 362 K and wide supercooled liquid regions ΔT, (ΔTx = Tx - Tg, where Tx is the onset temperature of crystallization) of about 80 K. Compared with ternary La-Al-Cu and Ce-Al-Cu systems, significant improvement of GFA for the (La-Ce)-Al-Cu system is caused by the coexistence of similar elements La and Ce, and the mechanism is discussed from a thermodynamic viewpoint.