Anomalously slow crystal growth of the glass-forming alloy CuZr

CG Tang and P Harrowell, NATURE MATERIALS, 12, 507-511 (2013).

DOI: 10.1038/NMAT3631

Our ability to exploit the benefits of metallic glasses(1) depends on identifying alloys of high glass-forming ability (GFA). So far, the established empirical correlations of GFA (ref. 2) are statistical guides at best and lack a microscopic rationale. Although simulations have the potential to provide this physical insight into the maximum crystallization rate, crystal nucleation is often too slow to be observed. In contrast, measuring the growth rate of a planar crystal surface represents an accessible route to understanding ordering kinetics. Here we use molecular dynamics simulations to show that the crystal growth rate for an important binary glass former, CuZr, is significantly slower than that of a poor glass former, NiAl. In accounting for this difference, we find that the crystal/liquid interface in NiAl exhibits a significantly greater width than that of CuZr. Our results suggest that the crystal/liquid interfacial structure exerts an important influence on the GFA of alloys.

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