Spherulitic crystallization behavior of a metallic glass at high heating rates

► Investigated glass crystallization over 4 orders of magnitude in heating rate. ► Low heating rates produce nanocrystals; high heating rates produce spherulites. ► Spherulites form at heating rates 1000x higher than the critical cooling rate. ► Spherulite formation activation energy is much lower than nanocrystallization. ► The number density of quenched-in nuclei during casting is ∼1014 m−3.