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The present work studied the synthesis of Fe-Ni Invar alloy nanopowder by the electrical explosion of wire (EEW) in deionized water. X-ray diffraction (XRD) was used to investigate the phase of the nanopowder. It indicated that the assynthesized nanopowder had c-Fe-Ni solid solution and FeO phase. Pure c-Fe-Ni phase was obtained when the as-synthesized powder was reduced under the hydrogen at 700°C for 30 min. Particle sizes of the as-synthesized and the reduced powders were observed by electron transmission microscope. The as-synthesized and the reduced nanopowders were in a nearly spherical shape with average size of 32.5 and 180 nm, respectively. The as-synthesized particles had a core-shell structure that was composed of c-Fe-Ni in the core and FeO in the shell. The alloy compositions of the wire before exploding and the reduced nanopowder determined by electron probe microanalysis were almost the same. The hysteresis loop of the as-synthesized nanopowder, the hydrogen-reduced nanopowder and the sintered sample were examined with a vibrating sample magnetometer. The sintered sample had the smallest coercivity with a value of 14.26 Oe.

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This paper presents a novel single-step method for preparation copper nanofluids by electrical explosion of wire in liquid. Three types of fluids were used as a medium of the wire explosion process: deionised water, cetyl trimethyl ammonium bromide (CTAB) solution 0.001 M and ethylene glycol. The X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and UV-vis spectroscopy were used to investigate the properties of the nanofluids. Pure copper phase was detected in the nanofluids using ethylene glycol and mixture of copper and oxide phase was observed in the nanofluids using water and CTAB solution. FE-SEM analysis showed that size of particles formed in ethylene glycol was about 90 nm, the smallest in three samples.

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