The Effect of Ion Irradiation on Nanocrystallization and Surface Relief of a Ribbon from Fe72.5Cu1Nb2Mo1.5Si14B9 Alloy

Abstract

Using the methods of X-ray diffraction and atomic force microscopy, the process of crystallization of an amorphous Fe_72.5Cu₁Nb₂Mo_1.5Si₁₄B₉ alloy irradiated with accelerated Ar⁺ ions is investigated. It is found out that an irradiation by the Ar⁺ ions with the energy 30 keV at the ion current density 300 μA/cm² (fluence 3.75·10¹⁵ cm^–2, irradiation time ~2 s, ion-beam short-duration heating up to 350°С, which is 150°С lower than the thermal crystallization threshold) results in a complete crystallization of this amorphous alloy (throughout the bulk of a 25 μm ribbon) followed by precipitation of solid solution crystals of α-Fe(Si), close in its composition to Fe₈₀Si₂₀, stable phase of Fe₃Si, and metastable hexagonal phases. By the methods of atomic force and scanning tunneling microscopy it is shown that nanocrystallization caused by ion irradiation is accompanied by surface relief changes both on the irradiated and unirradiated sides of the Fe_72.5Cu₁Nb₂Mo_1.5Si₁₄B₉ alloy ribbon at the depth exceeding by a factor of 10³ that of the physical ion penetration for this material. The data obtained, taking into account a significant temperature decrease and multiple acceleration of the crystallization process, serve an evidence of the radiation-dynamic influence of accelerated ions on the metastable amorphous medium.