Microstructure, decomposition, and crystallization inZr41Ti14Cu

Abstract

The microstructure as well as the decomposition and crystallization of the Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass ͑MG͒ has been investigated. The effects of the decomposition on the subsequent crystallization are determined. Reduced density function analyses for the MG, and the decomposition and crystallization in the MG have been made by means of electron-diffraction intensity measurement with imaging plate to determine the local atomic structure and its development in the course of the decomposition and crystallization. The microstructural characteristics of the MG are obtained demonstrating the difference between the bulk MG and conventional MG. The origin of the large glass forming ability of the alloy and the effect of the phase separation on the crystallization are discussed based on the obtained local atomic structural information of the MG.

Stability of ZrTiCuNiBe Bulk Metallic Glass upon Isothermal Annealing Near the Glass Transition Temperature

“…Primary nanocrystallization, 9 phase separation, [9][10]15 and local microstructural change from short-range order to medium-range order 16 depending on annealing conditions have been observed in the supercooled liquid region of the BMG. The large density difference (the relative density change is about 1.0%), elastic constants changes, and XRD and DSC results provide additional evidence that nanocrystalline precipitation occurs in the BMG reheated near to T g .…”

“…This suggests that a microstructural change happens when the BMG is annealed for a prolonged time in the supercooled liquid region, and the annealed BMGs have smaller first nearest-neighbor distance compared with the as-prepared state indicating a close-packed atomic environment. Previous work [9][10][11] shows that the BMG separates into two different amorphous phases when annealed in the supercooled liquid region at the earlier stage of the annealing (0-3 h). The decomposed amorphous phases have different short-range orders and compositions compared with the as-prepared BMG.…”

“…The decomposed amorphous phases have different short-range orders and compositions compared with the as-prepared BMG. 10 The phase separation, which is controlled by atomic mobility, favors the subsequent crystallization and causes the precipitation of nanocrystalline particles in the BMG. The nucleation and growth of Zr-rich crystalline phases 9 occurs whose compositions are such that they shift the average nearest-neighbor distance of the remaining amorphous alloy by preferentially depleting Zr with a large atomic volume.…”

Atomic-Scale Structural Evolution and Stability of Supercooled Liquid of a Zr-Based Bulk Metallic Glass

“…Since the advent of multicomponent bulk metallic glasses (BMGs) in the early 1990s, the stability of their glass-forming liquids with respect to crystallization have been extensively investigated owing to its scientific and technological importance [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Despite substantial dedicated effort, one question yet to be resolved is why some BMGs exhibit a high crystallization resistance while others do not [12,15].…”

Anomalous thermal stability of Nd–Fe–Co–Al bulk metallic glass

“…it occurs at a higher temperature than for most of the other BMGs, because of the larger chemical difference between the supercooled liquid and the equilibrium phases. An amorphous phase separation (APS) process then tends to occur to reduce the free energy of the system [40,41]. This APS takes place in the casting process due to the relatively slow cooling rate upon copper mold casting BMG, and leads to the inhomogeneity of the composition in the as-cast amorphous state.…”