Structural formation of Ti – Al – B composite as a function of the method used to obtain and introduce Boron

Abstract

This paper looks at the possibility of obtaining ternary borides with a nanolaminate structure (of the MAX phase type) in the Ti – Al – B system by self-propagating high-temperature synthesis (SHS). Different methods were used for introducing boron and titanium. Thus, they were introduced in the form of powders of elemental boron and titanium and in the form of compounds of TiH2 and AlMgB14 (“hydride technology”). Titanium hydride was obtained by annealing the powder at 450 оС in a continuous hydrogen flow. The obtained titanium hydride was mixed with aluminum powder and pressed at a pressure of 6.63·106 Pa. Workpieces with a diameter of 2 cm and a thickness of 0.2 cm were produced, which were then annealed under a programmable temperature regime at 620 оС (below the aluminium melting temperature). The second type of workpieces was obtained by combining titanium hydride with aluminum powder and B/AlMgB14. This mixture was then pressed at a pressure of 6.63·106 Pa. The resulting workpieces (with a diameter of 2 cm and a thickness of 0.2 cm) were annealed at 1.000 оС. The high-boron compound of AlMgB14 was obtained by SHS. The use of the hydride technology leads to the formation of new phases: borides and titanium aluminides. Ternary borides (Ti2AlB) were not found. The authors use the results of a microstructural study and an X-ray energydispersive analysis of the samples, as well as element distribution maps, to demonstrate the possibility of obtaining ternary laminate compounds (of the MAX phase type) in the Ti – Al – B system by SHS using elemental powders. The SHS products are not a homogeneous ternary phase. Ternary laminate borides are located in the Ti3Al intermetallide matrix. All the synthesis techniques used in this research lead to the formation of multiphase products.The work was carried out within the framework of the State assignment of the Tomsk Scientific Center of Siberian branch of RAS, project No. 121031800 148-5 (synthesis of samples via SHS method).The work was carried out under financial support of the Ministry of Education and Science of Russian Federation within the framework of the State assignment No. FSWM-2020-0028.Investigations of microstructure via SEM method were conducted using the equipment of the Tomsk regional common use center of the National Research Tomsk State University (the grant of the Ministry of Education and Science of Russian Federation No. 075-15-2021-693 (No. 13.ЦКП.21.0012)).