Nano-Crystallization and Stability of an Amorphous Phase in Fe-Nd-B Alloy under 2.0 MeV Electron Irradiation

Abstract

Formation of nano-structure in melt-spun ternary Fe-Nd-B alloys was examined focusing on electron irradiation induced crystallization. In Fe_82.2Nd_7.1B_10.7 (Fe/Nd/B = 23/2/3), Fe₇₇Nd_4.5B_18.5 and Fe₇₁Nd₉B₂₀ alloys, melt-spun amorphous phase changed to a crystalline phase during electron irradiation and nano-structure was formed. The crystalline phase in melt-spun Fe₈₆Nd₉B₅ and Fe_82.4Nd_11.8B_5.8 (Fe/Nd/B = 14/2/1) alloys was unstable under electron irradiation and electron irradiation induced amorphization occurred. With the further irradiation, crystallization from the amorphous phase was induced resulting in forming nano-crystalline structure. The onset total dose for the irradiation induced crystallization, namely, stability of the amorphous phase against electron irradiation depends strongly on the Fe-ratio, crystallization temperature, mismatch entropy and mixing enthalpy of the alloys.