Features of the structure of phase formation in the Fe—Ga—Al system

Abstract

Aluminium alloying of alloys on Fe–Ga based materials currently is the most promising direction in the field of development of actual ferromagnetic materials with steadily increased operational characteristics. Ingots of a ternary alloy with a composition of 50% (at.)—Ga—35% (at.) Fe—Al were obtained by fusing the pre-made ligature Fe—50% (at.) Ga with aluminium powder in mass ratio 1 : 1, at temperature 1000 oC in a neutral environment (argon). The conditions under which the alloying of aluminium with the ligature took place provided additional refinement of the components, in particular from oxygen, by binding it with an excess amount of reagents reactive to oxygen. The peculiarities of the formation of the structure were studied and it was established that each of the 3 phases that make up the material contains all three main components of the system. The interplanar distances,dexpfor each of the detected peaks on the diffractogram of the alloy were calculated according to the Wolff-Bragg formula. It was found that the temperature intervals in which thermal effects are recorded are close to the temperatures of phase transformations in the Fe—Ga system. Drawing analogies with phase transformations in the Fe-Ga binary system, an assumption was made regarding the similarity of the nature of phase transitions at temperatures up to 1000 °C in the experimental alloy and in the Fe-Ga binary system in the concentration range of 45—50% (at.) gallium. The microhardness of the phases found in the microstructure of the alloy is 8,05 ± 0,25; 9,15 ± 0,25 and 6,25 ± 0,15 GPa, which is significantly higher than the hardness of all intermetallics, that exist in the Fe—Ga system and corresponds to the hardness level of iron aluminides enriched with aluminium, such as Fe2Al5, FeAl2 and FeAl3. Keywords: Fe, Al, Ga, intermetallics, microstructure, phase formation, crystal lattice parameters, microhardness.