Electric explosion of wires (EEW) takes place upon exposure to intense short current pulses. Besides melting and evaporation of the original metal, various chemical reactions may take place with the ambient media as well. EEW of various crystalline wires have been studied in detail already. Study of the EEW on amorphous ribbons may also attract interest. Additional questions can be raised, e.g. whether the original amorphous state of the starting ribbons is preserved. In this context EEW of four ribbons were performed, namely (1) Fe50Co50, (2) Fe45Co45Zr7B3 (HITPERM), (3) Fe73.5Si15.5B7Nb3Cu1 (FINEMET), and (4) Fe71.6Si3.4C12.3Mn0.6B12.2 (bulk amorphous). Primarily water was used as quenching media, sample (4) was quenched in ethylene glycol as well. Products were analyzed with XRD, SEM, HRTEM and Mössbauer spectroscopy. The latter method provides primarily a gross analysis of the composition and phases present, whereas informations for atomic range can be extracted from HRTEM studies. EEW of sample (1 - Fe50Co50) results in reaction with water, oxidation of iron is preferred in comparison to cobalt. In products of sample (2 – HITPERM) primarily crystalline phases were detected by Mössbauer spectroscopy. HRTEM studies reveal presence of core-shell nanospheres, shells composed from the oxidation products. In the products of (3 – FINEMET) sample crystallization is also dominant– uppermost 20 % spectral area can be attributed to distribution of magnetic hyperfine field values in metallic components. HRTEM study reveals primarily the presence of crystalline nanoparticles. Explosion of sample (4 – bulk amorphous) in water results in oxidation of significant extent. In contrast, in glycol, carbide formation is predominant with various distributions in parameters of Mössbauer spectra. HRTEM studies reveal the dominant presence of crystalline iron carbide particles in carbonaceous shells. Nanoparticles, displaying electron diffraction images characteristic for amorphous structures were detected only in minor amounts. These combined studies can be summarized in a comparison. Relied on Mössbauer spectra, existence of amorphous phase can be suggested in significant extents (c.f distributions in the parameters). However, in a distinct contrast, the atomic scale HRTEM reveals the overwhelming presence of crystalline nanoparticles in broad variety of structures and compositions (which may partly be reflected in the distributions of Mössbauer parameters, too).

Electric explosion of amorphous iron alloy ribbons in water and glycol

ACS Fall 2021

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