Microstructural study of the low-temperature nanocrystallization of amorphous Fe78B13Si9

Abstract

The amorphous Fe78B13Si9 (Metglas 2605S‐2) alloy is treated by high current density electropulsing and the preliminary, partial, and full nanocrystallization can be achieved at temperatures lower than the bulk crystallization temperature by isothermal annealing. Analysis of Mössbauer spectra along with XRD measurement and TEM observation is presented. The preliminary crystalline product is the disordered b.c.c. Fe‐based solid solution, probably containing a trace amount of B. In the partially and fully crystallized samples, α‐Fe(Si), t‐Fe2B, and also a small amount of t‐Fe3B appear. The hyperfine magnetic field distribution P(H) of the residual amorphous phase in the crystallized sample takes a distinct bimodal type. It was suggested that the secondary peak at the higher field side can be associated with Fe‐rich clusters in the residual amorphous phase of the preliminarily crystallized sample and that the lower field side is caused by the local segregation of some Si and B atoms in the residual amorphous phase excluded during the crystallization processes of the partially and fully nanocrystallized samples.

Pb phase coarsening in eutectic Pb/Sn flip chip solder joints under electric current stressing

“…Koppenaal and Simcoe (1963) reported that a d.c. current of $10 3 A/cm 2 enhanced the precipitation rate of an Al-4wt.%Cu alloy determined by resistivity measurements. The precipitation rate increases in an approximately linear fashion with current density beyond a critical value of $10 3 A/cm 2 Electric current is also found by researchers (Lai et al, 1989;Lai et al, 1995;Teng et al, 1996) to accelerate crystallization of rapidly quenched amorphous alloys (Fe-Si-B). But until today our understanding of the detailed atomic mechanisms pertaining to the effects of a current on phase transformation is still very rudimentary (Conrad, 2000).…”

Crystallization under electropulsing suggesting a resonant collective motion of many atoms and modification of thermodynamic parameters in amorphous alloys

“…[2][3][4][5][6][7] Repetition of electropulsing with a duration of 60-100 s and a peak current density of 10 9 A/m 2 brings about a decrease in the crystallization temperature by 150-170 K for a-Fe-Si-B alloys. [8][9][10][11][12] Both the effects of a dc electric current and repetition of electropulsing may be similar to each other after taking into account difference in the current density and the total time for passing current. The effects are much greater than can be explained by simple electromigration theory and suggest the enhancement of an electromigration effect through a collective motion of many atoms.…”

“…The effects are much greater than can be explained by simple electromigration theory and suggest the enhancement of an electromigration effect through a collective motion of many atoms. [1][2][3][4][5][6][7][8][9][10][11][12] Recent theoretical works on the thermodynamic effect of an electric current on the phase transformation in amorphous alloys report that metastable phases can manifest under influence of an electric current 13,14 or nanocrystalline growth may be a function of the current density. 15 However, present experimental knowledge is very poor for examination of the theoretical works.…”

Amorphous FeCoSiB for exchange bias coupled and decoupled magnetoelectric multilayer systems: Real-structure and magnetic properties

“…According to previous studies using M€ ossbauer spectroscopy on amorphous magnetic alloys with similar compositions nanocrystalline phases of FeSi, FeCo, and FeCoSi must be considered. [29][30][31] However, a clear assignment is not possible from our data as demonstrated by the comparison of characteristic d-values for each phase presented in Table TSII of the supplementary material. 25 …”