Electron Irradiation Induced Nano-Crystallization in Fe<SUB>77</SUB>Nd<SUB>4.5</SUB>B<SUB>18.5</SUB> Metallic Glass

Abstract

Phase transformation behavior in Fe 77 Nd 4:5 B 18:5 metallic glass during electron irradiation and thermal annealing was investigated. Crystallization from glassy phase during thermal annealing occurred in multi-stages forming -Fe and several intermetallic compounds. Electron irradiation induced crystallization occurred at 298 K and nanostructure composed of -Fe, Nd 2 Fe 14 B and Fe 17 B 2 precipitates embedded in amorphous matrix was formed. The electron irradiation induced crystallization behavior was discussed by atomic displacement due to electron knock-on effect and atomic diffusion via free volume in amorphous phase.

Nanocrystallization of Cu<SUB>50</SUB>Zr<SUB>45</SUB>Ti<SUB>5</SUB> Metallic Glass Induced by Electron Irradiation

“…Similar results have been obtained in the studies on Zr-based and Fe-based metallic glassy alloys. 10,11,16) CuZr particles exhibited a non-linear growth with time, where the growth rates at time t > 1200 s became to an order of 1 Â 10 À13 m s À1 in Fig. 5 and the particle size saturated at about 8 nm (Fig.…”

“…11,16) The activation process of atomic diffusion under electron irradiation affects the nucleation and growth rates of crystalline phases. Considering atomic species and direction in atomic movement, highly frequent homogeneous atomic displacement in a glassy phase can be induced by electron irradiation.…”

“…The difference between these rates under electron irradiation is believed to be small. 11,16) This is one reason for the subsequent low growth rate of the monoclinic CuZr under electron irradiation. In addition, interstitials and vacancies are continuously produced by electron irradiation in crystalline precipitates.…”

“…Crystallization of the glassy phase is induced not only by heat treatments but by other methods such as electron irradiation, [9][10][11] ion irradiation, 12) electropulsing 13) and high pressure. 14) It has been demonstrated that electron irradiation can induce nanocrystallization in metallic glasses in which nanoscale structures cannot easily be realized by heat treatments.…”

“…14) It has been demonstrated that electron irradiation can induce nanocrystallization in metallic glasses in which nanoscale structures cannot easily be realized by heat treatments. 10,11) However, there are few reports on electron irradiation effects on structural changes in metallic glasses. In this study, we investigate the microstructural changes of a Cu 50 Zr 45 Ti 5 metallic glass under electron irradiation.…”