Viscous Flow Behavior and Workability of Mg-Cu-(Ag)-Gd Bulk Metallic Glasses

Abstract

) bulk metallic glasses in the supercooled viscous region under the loading condition were investigated using the thermomechanical analyzer. In this study, the supercooled viscous temperature windows, the minimum viscosity, the fragility parameter, and the deformability parameter would all be degraded with increasing Ag addition, leading to the negative factors for the micro-forming and nano-imprinting practices. The base Mg 65 Cu 25 Gd 10 alloy appears to be more promising than the Ag containing alloys when the viscous forming is under consideration.

Recent progress in metallic glasses in Taiwan

“…The viscous flow behavior and thermomechanical properties of Mg 65 Cu 25Àx B x Gd 10 (x ¼ 0 and 3 at%) [88] and Mg 65 Cu 25Àx Ag x Gd 10 (x ¼ 0, 3, 10 at%) [89] BMGs in the supercooled liquid region have also been investigated. It is found that the fragility of the supercooled liquid is reduced by the boron or silver addition, thus degrading the deformability.…”

Measurement and calculation of the viscosity of metals—a review of the current status and developing trends

“…Besides the two major methods described above, among the other methods that are used for the viscosity measurements of liquid metals, the one using an isothermal compressive test is found to be also widely used, but only for semisolid state metals [10][11][12][13][14][15][16]. In this method, the compression curves of semi-solid samples at various temperatures at given compression rates are experimentally obtained.…”

“…Chhabra et al [67] derived values of η 0 and E from experimental data for Ag, Al, Au, Bi, Ca, Cd, Co, Ca, Cu, Fe, Ga, Ge, Hg, In, K, Li, Mg, Na, Ni, Pb, Pu, Rb, Sb, Sn, Tl and Zn. Even for those metals whose data of η 0 and E are not known, it is very easy to determine the two numbers by doing backwards calculations using (13), with only two measuring points at two different temperatures.…”

“…Apart from those methods, no new method has been found for measuring the viscosity of liquid metals and alloys. But for semi-solid state metals, the isothermal compressive experimental method is another choice for their viscosity measurements [10][11][12][13][14][15][16]. With the developments of casting techniques like thixocasting and twin roll casting, which use semi-solid metals and alloys for manufacturing light-metal parts, the research on the viscosity data of semisolid state metals and alloys became more important.…”