Viscous flow behavior and thermal properties of bulk amorphous Mg58Cu31Y11 alloy

The viscous flow behavior of the Mg58Cu31Y11 bulk amorphous rods in the supercooled viscous region is investigated using differential scanning calorimetry (DSC) and thermomechanical analyzer (TMA). Below the glass transition temperature, Tg, a linear thermal expansion coefficient of 3 ± 1 × 10−6 m/m K was obtained. In contrast, significant viscous deformation occurred as a result of a compressive load above Tg. The onset, steady state, and finish temperatures for viscous flow, determined by TMA, are slightly different from the glass transition and crystallization temperatures measured by DSC. The appropriate working temperature for microforming as determined by the steady state viscous flow temperature is about 460–474 K. The effective viscosity within this temperature range is estimated to be about 107–109 Pa s, and it increases with increasing applied stress. The onset, steady state, and finish temperatures all decrease with increasing applied stress, suggesting accelerated crystallization in the present Mg58Cu31Y11 under stress.