Synthesis reactions of Cr2AlC from Cr–Al4C3–C by pulse discharge sintering

The reaction process of ternary compound Cr2AlC synthesis was studied. Powder mixture of Cr, Al4C3 and graphite at the composition of Cr:Al:C = 2:1.1:1 was processed by pulse discharge sintering in vacuum in the temperature range of 850 to 1350 °C. The synthesized materials were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrum (EDS) system. It was found that the amount of Cr2AlC phase increased significantly in the temperature range of 950 to 1150 °C at the consumption of Cr and Al4C3 as well as an intermediate phase Cr2Al. Predominantly single-phase Cr2AlC with small amount of Cr7C3 was obtained as the sintering temperature is above 1250 °C. It is presumed that Cr2AlC phase is formed near Al4C3 particle by the diffusion of Cr and the reaction of the diffused Cr with Al4C3.