Multistage Devitrification Behavior of Mg65Cu25Tb10 Bulk Metallic Glass

Abstract

The devitrification of Mg 65 Cu 25 Tb 10 bulk metallic glass (BMG) has been studied by timeresolved small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) simultaneously. By analyzing the interference peaks on SAXS patterns and the Bragg peaks on WAXS patterns, it is found that devitrification initiates by activation of quenched-in shortrange orders. Crystallization proceeds in three stages. During stage I, icosahedral clusters are formed that transforms to a quasi-crystalline 1/1 approximant during stage II, accompanied by the formation of cubic TbMg 3 . In stage III, the 1/1 approximant transforms to a 2/1 approximant. The orthorhombic CuMg 2 phase is formed at a higher temperature when the quasicrystalline phase starts to decompose. Pair distribution functions were evaluated to demonstrate these structural evolutions in real space.

Influence of structural relaxation on atomic mobility in a Zr41.2Ti13.8Cu125Ni10.0Be22.5 (Vit1) bulk metallic glass

“…Evidence for decomposition was also obtained in Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 bulk metallic glass [68]. In contrast, in Cu 43 Zr 43 Al l7 Ag 7 , crystallization is a single step phase transformation [69,70], while in Mg 65 Cu 25 Tb 10 , crystallization proceeds in three stages [71]. During stage I, icosahedral clusters are formed that transforms to a quasi-crystalline approximant during stage II and finally the orthorhombic Mg 2 Cu phase is obtained.…”

Multiscale structures and phase transitions in metallic glasses: A scattering perspective

“…When heating an MG to the supercooled liquid region between glass transition T g and crystallization temperature T x , the structure of glass first relaxes and then crys-017104-3 tallization takes place. [30][31][32][33][34][35] Novel microstructures and interfaces with an unusually large number of nanoscale precipitates could be synthesized using the principles of relaxation and crystallization studies. However, the atomic-to nanoscale mechanisms of relaxation and crystallization for MGs are long-standing issues for two reasons.…”

Crystallisation process in Mg60Cu30Gd10-xNdx(x = 0, 8.5) amorphous alloys

“…In some cases, the presence of nanocrystals in the amorphous matrix can enhance the strength of the material [9], so it is of interest the study of the early crystallisation stages in order to determine the crystalline phases involved. For Mg 65 Cu 25 Tb 10 [10] the formation of quasicrystalline phases is reported, that transform to Mg 2 Cu, Mg 3 Tb and unidentified phases during a second crystallisation stage. For Mg 65 Cu 25 Y 10 amorphous alloy, Murty and Hono [11] suggest the formation, as crystallisation products, of an Y containing Mg 2 Cu, via polymorphic crystallisation.…”