DENSIFICATION AND PHASE EVOLUTION OF SHS DERIVED Ti2AlN ACTIVE PRECURSOR POWDERS DURING HOT PRESSING PROCESSES

摘要

Ti_2A1N belongs to the interesting group of ternary nanolaminate materials called MAX phases. These compounds are characterised by heterodesmic chemical bonding and thanks to this fact they posses unique set of properties situating them between metals and ceramics. One of the best methods of synthesizing fine active precursors powders of these materials is Self-propagating High-temperature Synthesis (SHS). This method utilizes exothermal effect of the chemical reaction in adiabatic conditions and allows obtaining many compounds such as nitrides, carbides, composites, intermetallics, etc. at low energy consumption and with high efficiency and at relatively short time. In this paper authors would like to present results of investigation on densification and phase evolution phenomenon during hot pressing of various SHS derived Ti_2AlN active precursor powders. Powders were synthesized in filtration combustion regime with local ignition system using different nitrogen pressure and various chemical reactions. The selected powders were hot-pressed at temperatures range from 1250 to 1400°C. The phase evolution and apparent densities of obtained samples were examined in order to establish the optimal conditions for manufacturing of near single phase Ti_2A1N material.