Powder Composition Structurization of the Ti-25Al-25Nb (at.%) System upon Mechanical Activation and Subsequent Spark Plasma Sintering

Abstract

The results of a study of the microstructure evolution of pre-mechanically activated elementary powders based on the Ti-25Al-25Nb (at.%) compositions differing in the particle size of the aluminum (Al) component are presented. It was found that during the mechanical activation, most of the Al was dissolved in the Ti and Nb lattices by interpenetration with the formation of solid solutions (Ti, Al) and (Nb, Al). It has been established that an increase in temperature to 1400 °C, when sintering powder materials based on the Ti-Al-Nb system, leads to a sharp increase in the temperature of Al particles, as a result of the melting of which it is impossible to control the phase formation, which ultimately leads to the difficulty of obtaining the required product. It was determined that in the process of spark-plasma sintering of mechanically activated compositions, intermetallic compounds are formed based on phases ‒ α2, B2 and O, and with an increase in the sintering temperature, their morphology and distribution in the alloy volume change.