Grain sizes of magnetic alloys electrodeposited in an ionic liquid (IL) can be varied in a wide range by changing the deposition conditions. A deposition of single domain crystals of soft magnetic materials is interesting due to expected nearly zero magnetization reversal power losses. By changing the deposition condition the composition of the deposited alloy can be varied.
Iron (Fe) samples were deposited form the IL 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate, [Py1,4]TfO, on a copper substrate. A solution of FeCl2 was used at a temperature of 358 K. In addition Iron–aluminium (FeAl) alloys were electrodeposited using the same IL on a copper substrate, but a solution of (0.2 M FeCl2 + 2.75 M AlCl3) / [Py1,4] TfO was used at a temperature of T = 373 K. Due to the moisture sensitivity of the IL and the susceptibility to corrosion of the deposit, the preparation was done in a glove box under Ar atmosphere
The onset of Fe deposition was found to occur at a potential of -0.52V, the onset of FeAl codeposition was found to be around -0.95V and the onset of bulk Al deposition was found to be at -1.9V.
For Fe and FeAl alloys a deposit of approximately 10µm thickness after 2 hours of electrodeposition at the working potential, -1.7V and -1.4 V, was obtained; respectively. In addition, for FeAl alloys, at the chosen potential of -1.7V, a Fe-2.5wt%Al alloy was obtained.
Grain sizes of around 50-75nm were estimated from scanning electron microscopy, X-ray diffraction and magnetic measurements.
Samples of Fe and FeAl alloys were produced with different electrodeposition voltages and during different periods of time.
The Fe and FeAl deposits were characterized by cyclic voltammograms, scanning electron microscopy (SEM), X-ray diffraction (XRD), magnetic measurements (MM), and mechanical spectroscopy (which involves the simultaneous measurement of the mechanical energy losses and the elastic modulus as a function of temperature). The mechanical spectroscopy response reveals relaxation processes both from the copper substrate and from the deposited iron and iron-aluminium. The anelastic results from mechanical spectroscopy are coupled to SEM, XRD and MM in order to explore the effect of the microstructure upon the magnetic response in these metals and alloys regarding their use as functional materials.