Formation Mechanism of High-Purity Ti₂AlN Powders under Microwave Sintering

In the present study, high-purity ternary-phase nitride (Ti₂AlN) powders were synthesized through microwave sintering using TiH₂, Al, and TiN powders as raw materials. X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were adopted to characterize the as-prepared powders. It was found that the Ti₂AlN powder prepared by the microwave sintering of the 1TiH₂/1.15Al/1TiN mixture at 1250 °C for 30 min manifested great purity (96.68%) with uniform grain size distribution. The formation mechanism of Ti₂AlN occurred in four stages. The solid-phase reaction of Ti/Al and Ti/TiN took place below the melting point of aluminum and formed Ti₂Al and TiN_0.5 phases, which were the main intermediates in Ti₂AlN formation. Therefore, the present work puts forward a favorable method for the preparation of high-purity Ti₂AlN powders.