Structures at Glassy, Supercooled Liquid, and Liquid States in La-Based Bulk Metallic Glasses

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 41; no. 7; pp. 1634 - 1639
• Main Authors: Jiang, Q.K., Chang, Z.Y., Wang, X.D., Jiang, J.Z.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2010; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Metallic Materials; Nanotechnology; Structural Materials; Surfaces and Interfaces; Symposium: Bulk Metallic Glasses VI; Thin Films; Glass Form Ability; Linear Expansion Coefficient; Supercooled Liquid Region; Supercooled Liquid; Coordination Shell
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-009-0041-9

Local atomic structures at glassy, supercooled liquid, and liquid states for La-based bulk metallic glasses (BMGs) have been investigated by in-situ high-temperature X-ray diffraction. It is found that the coordination number of about 15.1 ± 0.1 for the La 62 Al 14 Cu 11.7 Ag 2.3 Ni 5 Co 5 alloy does not depend on temperature up to liquid temperature, while it decreases slightly with temperature for the La 62 Al 14 Cu 24 and La 62 Al 14 Cu 20 Ag 4 alloys. The S ( q ) data recorded at the supercooled liquid region can be well described by the Debye theory. For the three alloys, the volume expansion coefficient and the slopes of radii variation for the first to third nearest neighboring coordination shells show differences at glassy-to-supercooled liquid transition, while no obvious changes were detected at supercooled liquid-to-liquid transition for them. The linear expansion coefficient value ( β   =  1.6 ± 0.1 × 10 –5  K –1 ) below the glass transition temperature deduced from S ( q ) data is consistent with that detected by the dilatometer ( β   =  1.25 × 10 –5  K –1 ) for the La 62 Al 14 Cu 11.7 Ag 2.3 Ni 5 Co 5 BMG.