Evolution of spatial heterogeneity in a Zr-based metallic glass

We report an investigation of the evolution of spatial heterogeneities in bulk amorphous Zr54.5Ti7.5Al10Cu20Ni8. The glassy state is characterized by fluctuations on a 1 nm scale. Metastable non-crystalline clusters are activated to grow at temperatures near the glass transition. Impinging clusters form boundaries where additional free volume is localized. At high volume fraction of impinging clusters enhanced diffusion occurs on the cluster boundaries resulting in a crystallization of the large clusters having a mean size of 2.5 nm.