Microstructural investigation of an as-cast Cu47.5Zr47.5Al5 bulk metallic glass (BMG) reveals two amorphous phases formed by liquid phase separation. The morphology of the phase separated amorphous regions is spherical with 10–20nm in size. These areas are homogeneously distributed throughout the sample. Moreover, a macroscopic heterogeneity also occurs along with the nano-scale liquid phase separation. The macroscopic heterogeneity can be distinguished from the different degree of the chemical fluctuations in the sample, and the existence of nano-scale crystals of less than 5nm in size. Presumably, both the macroscopic heterogeneity and the nano-scale phase separation enhance branching of the shear bands during deformation in the Cu47.5Zr47.5Al5 BMG.

We report a novel phenomenon in which minor element additions (∼1 at.%) can dramatically enhance the glass-forming ability (GFA) of CuZr(Al) metallic alloy, which can be cast into glasses with large cross-section sizes using a conventional casting method. The minor additions cause the liquidus temperature Tl to decrease from 1219 (for Cu50Zr50) to 1139 K [for (Cu50Zr50)92Al7Gd1], and the reduced glass transition temperature Trg (=Tg/Tl) of the alloys increases from 0.550 (for Cu50Zr50) to 0.613 [for (Cu50Zr50)92Al7Gd1]. The mechanism involved in the achievement of the superior GFA is explained by the stronger tendency of short-range ordering in the stronger microalloyed alloys as well as the thermodynamic and kinetic aspects.

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Despite the use of glasses for thousands of years, the nature of the glass transition is still mysterious. On approaching the glass transition, the growth of dynamic heterogeneity has long been thought to play a key role in explaining the abrupt slowdown of structural relaxation. However, it still remains elusive whether there is an underlying link between structural relaxation and dynamic heterogeneity. Here, we unravel the link by introducing a characteristic time scale hiding behind an identical dynamic heterogeneity for various model glass-forming liquids. We find that the time scale corresponds to the kinetic fragility of liquids. Moreover, it leads to scaling collapse of both the structural relaxation time and dynamic heterogeneity for all liquids studied, together with a characteristic temperature associated with the same dynamic heterogeneity. Our findings imply that studying the glass transition from the viewpoint of dynamic heterogeneity is more informative than expected.

The effects of high pressure ͑up to 5 GPa͒ on the mechanical properties of a typical Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass ͑BMG͒ have been investigated. It is found that the high-pressure pretreatment at room temperature can significantly improve the mechanical performance of the BMG. Particularly, the compressive plasticity of the BMG can be increased as large to as 12% by 4.5 GPa pressure pretreatment. The origin of the pressure effect on mechanical properties is studied.