Synthesis of Porous Composite Material with the Combustion of Titanium and Boron Powders and Nickel-Clad Aluminum Granules

摘要

Self-propagating high-temperature synthesis (SHS) in the Ni-Al-Ti-B system has been carried out. The aim of the study is to obtain, in one process step, a composite material with a ceramic and intermetallic framework and a developed porous structure in combustion mode from the boron-titanium-large nickel-clad aluminum granules powder system pressed by successive batch compaction method. The synthesis process is characterized by a stage nature, in which a highly exothermic reaction between titanium and boron form a boride matrix with developed open porosity and acts as a "chemical furnace" to maintain the reaction in the clad granules, in which nickel aluminides appeared. The aluminide melt impregnates the porous diboride matrix. The synthesis stages are reflected in the thermograms of the process. The final structure of the product has a multiscale porosity, a characteristic feature of which is large round pores (similar to 100-160 mu m in diameter) whose location corresponds to the position of clad granules in the initial powder system. Small (0.1-5.0 mu m) and some average-sized (up to 15 mu m) diboride matrix pores are filled with nickel aluminides. The resulting material has a composite structure of the type of interpenetrating frameworks-ceramic (TiB2) and aluminide (NiAl, Ni3Al). The diboride matrix is formed by chaotically oriented hexagonal small crystals predominantly 0.2-1.0 mu m across in size. At the boundaries with macropores, crystal diboride grains increase in size up to 2-6 mu m in diameter and 0.5-2.0 mu m in thickness, acquiring a more pronounced platelike shape. The main size of intermetallic interlayers filling the pores between the diboride crystal grains is similar to 0.2-1.0 mu m.