A eutectic reaction is a basic liquid-solid transformation, which can be used in the fabrication of high-strength in situ composites.

In this study an attempt was made to ensure directional solidification of Fe-C-V alloy with hypereutectic microstructure. In this alloy, the

crystallisation of regular fibrous eutectic and primary carbides with the shape of non-faceted dendrites takes place. According to the data

given in technical literature, this type of eutectic is suitable for the fabrication of in-situ composites, owing to the fact that a flat

solidification front is formed accompanied by the presence of two phases, where one of the phases can crystallise in the form of elongated

fibres.

In the present study an attempt was also made to produce directionally solidifying vanadium eutectic using an apparatus with a very high

temperature gradient amounting to 380 W/cm at a rate of 3 mm/h. Alloy microstructure was examined in both the initial state and after

directional solidification. It was demonstrated that the resulting microstructure is of a non-homogeneous character, and the process of

directional solidification leads to an oriented arrangement of both the eutectic fibres and primary carbides.

It has been shown that the precipitation of bismuth orthovanadate from a fly ash leachate is a promising method of vanadium recovery. BiVO4 obtained after appropriate heat treatment can be sold as a pigment. The yield of recovery of solubilised vanadium is equal to 68% and the precipitate is free from nickel impurity. The precipitate is insoluble in the solutions with pH ≥ 3. In more acidic media the solubility of precipitate increases with the decreasing pH. The solubility of the precipitate increases also with the increasing concentration of chloride ions.

In this study, the effects of adding niobium and vanadium to Fe-based oxide dispersion strengthened alloys are confirmed. The composition of alloys are Fe-20Cr-1Al-0.5Ti-0.5Y2O3 and Fe-20Cr-1Al-0.5Ti-0.3V-0.2Nb-0.5Y2O3. The alloy powders are manufactured by using a planetary mill, and these powders are molded by using a magnetic pulsed compaction. Thereafter, the powders are sintered in a tube furnace to obtain sintered specimens.

The added elements exist in the form of a solid solution in the Fe matrix and suppress the grain growth. These results are confirmed via X-ray diffraction and scanning electron microscopy analyses of the phase and microstructure of alloys. In addition, it was confirmed that the addition of elements, improved the hardness property of Fe-based oxide dispersion strengthened alloys.

The paper presents the results of abrasive wear resistance tests carried out on high-vanadium cast iron with spheroidal VC carbides. The cast iron of eutectic composition was subjected to spheroidising treatment using magnesium master alloy. The tribological properties were examined for the base cast iron (W), for the cast iron subjected to spheroidising treatment (S) and for the abrasion-resistant steel (SH). Studies have shown that high-vanadium cast iron with both eutectic carbides and spheroidal carbides has the abrasion resistance twice as high as the abrasion-resistant cast steel. The spheroidisation of VC carbides did not change the abrasion resistance compared to the base high-vanadium grade.

The paper presents the results of tests on the spheroidising treatment of vanadium carbides VC done with magnesium master alloy and mischmetal. It has been proved that the introduction of magnesium master alloy to an Fe-C-V system of eutectic composition made 34% of carbides crystallise in the form of spheroids. Adding mischmetal to the base alloy melt caused 28% of the vanadium carbides crystallise as dendrites. In base alloy without the microstructure-modifying additives, vanadium carbides crystallised in the form of a branched fibrous eutectic skeleton. Testing of mechanical properties has proved that the spheroidising treatment of VC carbides in high-vanadium cast iron increases the tensile strength by about 60% and elongation 14 - 21 times, depending on the type of the spheroidising agent used. Tribological studies have shown that high-vanadium cast iron with eutectic, dendritic and spheroidal carbides has the abrasive wear resistance more than twice as high as the abrasion-resistant cast steel.

The cast alloys crystallizing in Fe-C-V system are classified as white cast iron, because all the carbon is bound in vanadium carbides. High

vanadium cast iron has a very high abrasion resistance due to hard VC vanadium carbides. However, as opposed to ordinary white cast

iron, this material can be treated using conventional machining tools. This article contains the results of the group of Fe-C-V alloys of

various microstructure which are been tested metallographic, mechanical using an INSTRON machine and machinability with the method

of drilling. The study shows that controlling the proper chemical composition can influence on the type and shape of the crystallized

matrix and vanadium carbides. This makes it possible to obtain a high-vanadium cast iron with very high wear resistance while

maintaining a good workability.

This paper presents the results of studies of high-alloyed white cast iron modified with lanthanum, titanium, and aluminium-strontium. The

samples were taken from four melts of high-vanadium cast iron with constant carbon and vanadium content and near-eutectic

microstructure into which the tested inoculants were introduced in an amount of 1 wt% respective of the charge weight. The study

included a metallographic examinations, mechanical testing, as well as hardness and impact resistance measurements taken on the obtained

alloys. Studies have shown that different additives affect both the microstructure and mechanical properties of high-vanadium cast iron.

Cast Hadfield steel is characterised by high abrasion resistance, provided, however, that it is exposed to the effect of dynamic loads.

During abrasion without loading, e.g. under the impact of loose sand jet, its wear resistance drops very drastically. To increase the abrasion

resistance of this alloy under the conditions where no pressure is acting, primary vanadium carbides are formed in the metallurgical

process, to obtain a composite structure after the melt solidification. The primary, very hard, carbides uniformly distributed in the

austenitic matrix are reported to double the wear resistance of samples subjected to the effect of a silicon carbide-water mixture.