Synthesis of Composite Material in Al–Ti–B System during Combustion of Titanium and Boron Powders and Aluminum-Clad Granules of VT6 Alloy

Abstract

Abstract—Self-propagating high-temperature synthesis (SHS) in the combustion mode was carried out in the mixtures consisting of titanium fine powders with dendritic particles and amorphous boron, Ti + 2B, with addition of aluminum-clad large spherical granules of titanium alloy VT6. The aim of the study was to obtain a composite material in one technological stage by SHS in the Al–Ti–B system. The synthesis in the combustion wave occurred stage-by-stage. Initially, a chemical reaction took place between boron and fine titanium; it resulted in a boride framework around large clad particles. Simultaneously, this reaction acted as a “chemical stove,” causing heating and melting of the cladding layer and the subsequent reaction of aluminum with titanium alloy granules. The melt appearing during the reaction in the clad granules spread along the pores and capillaries into the boride matrix. The nonmonotonic shape of the recorded thermograms reflects the stages of the synthesis process and the heterogeneity of the reacting mixtures. The synthesized material has a developed porous and composite structure, which can be seen from elemental, microstructural, and phase analyses. There are four scales in the pore size in the combustion product. Large spherical pores appear at the place of the granules. Owing to layer-by-layer compaction of the mixture, the ordered arrangement of coarse particles in the initial compacts causes an ordered arrangement of macropores in the synthesis product.