Influence of Thermal Annealing Conditions on the Processes of Phase Transformations in Aluminium-Magnesium Ceramics Doped with Scandium

Abstract

In modern materials science, much attention is paid to the production of new types of ceramics that have increased resistance to external influences, as well as high strength parameters. At the same time, among the ceramics one can single out aluminum-magnesium spinel, which has a unique combination of properties that open up opportunities for its use as structural materials in the nuclear industry and aircraft construction, as well as metallurgy in the manufacture of crucibles for smelting metals. It should also be noted that recently special attention has been paid to research aimed at improving the properties of these ceramics by doping or alloying them, which makes it possible to change their properties and increase resistance to external influences. The purpose of this study is to study the effectiveness of scandium doping of aluminum-magnesium spinel (MgAl₂O₄) obtained using the method of mechanochemical solid-phase synthesis, on changing the dynamics of phase transformation processes. The choice of ceramics based on MgAl₂O₄ spinel as objects of study is due to the great prospects for its use in structural materials science, due to the unique physicochemical and strength properties, and the addition of scandium to the composition of this ceramic makes it possible to increase resistance to external influences and increase crack resistance. Using the method of X-ray phase analysis, it was found that an increase in the annealing temperature of alumina-magnesium ceramics doped with scandium leads to an enrichment of the composition with the γ-phase of aluminum oxide, with the formation of a substitutional solid solution of the MgAl₂O₄/Al₂O₃ type, and also to a decrease in the concentration of the ScAlMgO₄ phase. At an annealing temperature of 1500°C, inclusions are formed in the composition of ceramics in the form of an MgAl intermetallic phase with a high degree of structural ordering of the crystal lattice (the deformation distortion factor is – 0.35 (compression strain)).