Phase Composition and Structure of Powder Materials of the Ti–Al–B/TiB2 System After Vacuum Sintering and High-Temperature Synthesis

Abstract

The structure and phase composition of powder materials of the Ti–Al–B system formed in the process of vacuum sintering and synthesis in the mode of high temperature self-propagating synthesis (SHS) are considered depending on the combination of components in the form of elementary powders (Ti, Al and B) and using the finished titanium diboride (TiB₂) compound. The proportions of the components were calculated in such a way that the number of interacting elements was sufficient to form a two-phase TiAl₃ + TiB₂ composition. When sintering the Ti + Al + TiB₂ mixture, the diboride is retained, but the presence of TiB is noted as a result of the redistribution of boron due to its migration into free titanium. It was discovered that sintering of compacts from the mixture based on elemental powders (Ti, Al and B) occurs under conditions of high exothermic effect, as a result of which the samples were destroyed. This made it possible to use this mixture under conditions of high-temperature synthesis in combustion mode. As a result of both vacuum sintering and SHS compacting, aluminide TiAl₃ and titanium diboride (TiB₂) are mainly formed from a mixture of elemental powders (Ti, Al and B). In this case, some transition phases can be observed. It is shown that after the synthesis of the Ti + Al + B mixture, it is possible to obtain a powder product from which compacts are well sintered while maintaining their shape with a slight shrinkage.