Now hydrogen is supposed to be one of the most likely substitutes for organic fuel for transport and energy in general. However, in order to switch to hydrogen energy, it is necessary to solve a number of science and technological problems. Such problems include, first and foremost, the production of a cheap hydrogen in mass quantities, storage and delivery of hydrogen, and its effective use.
There are several technological solutions of the problem of hydrogen storage. The analysis shows that one of the most promising methods of accumulation and storage of hydrogen is metal hydride technology, which consists in the accumulation of hydrogen in hydrogen storage alloys (HSA), with its release when the alloy is heated. Now the main efforts of the researchers are directed to achieve greater capacity of metal hydrides, improving sorption-desorption conditions and increasing the cyclic stability of hydrogen accumulators.
For a long time, the optimization of the properties of hydrogen storage alloys was carried out as a rule by changing their chemical composition. Recently, a significant step has been taken in the development of HSA, in particular, due to the amorphization of the structure, the researchers are achieve to increase the hydrogen capacity of Zr-based alloys by 1.8 times in comparison with samples of the same composition in the microcrystalline state.
The samples of hydrogen storage alloys by the method of intensive plastic deformation were produced
Method of samples fabrication
Alloys of zirconium with vanadium were obtained in two states - the stoichiometric alloy ZrV2 and the non-stoichiometric eutectic Zr0,6V0,4. Alloys were smelted in an arc furnace in an atmosphere of pure argon using a tungsten electrode.
Then, strips with 30-40 mm thick and 2 -3 mm width were obtained on the Lenta -2M from the ingots of the alloy.
The ZrV2 and Zr0,6V0,4 alloy strips were ground in a high-energy ball mill (see Figure 1) in a neutral medium, argon and ethanol.
Figure 1 - Photo of a high-energy ball mill with a container and sheaves for grinding
The following samples of the stoichiometric alloy ZrV2 and eutectic Zr0,6V0,4 were obtained and in the states:
alloy in cast state with grains diameter near 1-10 mm ( Fig. 2(a));
fast quenched in the form of plates 0.1 mm in thickness, 1 ... 3 mm in width and up to 5 mm in length (see Figure 2 (b));
cast alloy state, after grinding in a ball mill during 30 minutes in Argon and 30 min in ethanol. The view of a fine powder shown on Figure 2 (c));
Fast quenched samples after grinding in a ball mill during 30 minutes in argon and 30 min. in ethanol. The view of a fine powder sees on Figure 2 (d).
Figure 2 - Average form of the ZrV2 samples obtained: before (a, b) and after (in, g) grinding
Diffractometry researches of the samples
In ZrV2 alloys, the result of high-energy grinding depends on the initial state of the samples, specified below:
in a cast sample, grinding results in the formation of a nanocrystalline state with a size of the coherent scattering region in the Laves phase of 27 nm;
in a fast quenched sample a quasi-amorphous (X-ray amorphous with OCD <15 nm) phase is formed.
In the samples of the eutectic Zr0,6V0,4, grinding the alloys of both types, cast and fast quenched, leads to the formation of a quasi-amorphous phase.