High electronic excitation-induced crystallization in Fe_73.5Cu₁Nb₃Si_13.5B₉ amorphous alloy: II. Carbon cluster irradiation

We present a detailed study of the crystallization induced in an amorphous alloy by cluster ions. The formation of nanocrystalline iron boride phases was observed by transmission electron microscopy in an amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉ alloy irradiated up to ./DRECAM of 1 × 10⁹-2 × 10¹¹ clusters cm^-2 at room temperature with C_n (n = 5, 10, 60) carbon clusters at 20 MeV, but not after irradiation with C₆₀ fullerenes at 30 MeV. The high level of energy deposited in electronic excitations along the path of carbon clusters induces radial pressure waves in the vicinity of the projectile trajectories. The formation of nanocrystallites was interpreted as being due to a structural relaxation which occurs in the wake of the shock front. The mechanical stresses induced by the pressure wave destabilize the amorphous structure and drive the nucleation of nanocrystallites.