Fabrication and Properties of Cr_2AlC Ceramics

Cr2AlC ceramics were prepared by hot-pressing using Cr, Al and graphite powders as starting materials. The effects of composition and sintering temperature on the phase assembly and bulk density of the samples were studied. The results indicated that the phase assembly of the samples consisted of Cr2AlC, as a major crystalline phase, together with very small amount of Cr7C3 for the composition with less than 20at% excessive Al content, whereas it became a single Cr2AlC phase in the sample for the composition with more than 20at% excess Al. The bulk density of the samples decreased with the increase in excess Al in the composition. The hardness, flexural strength and Young's modulus of the sample hot-pressed at 1400℃for 1h for the composition Cr:Al:C=2:1.1:1 at room-temperature were 3.5GPa, 375MPa and 278GPa respectively. The electrical conductivity decreased linearly with the increase in temperature from 75K to 269K, which hinted that the electrical behavior of Cr2AlC likes that of metal. Its thermal properties were also determined.