Synthesis of high-purity, isotropic or textured Cr2AlC bulk ceramics by spark plasma sintering of pressure-less sintered powders

The synthesis of a high purity Cr2AlC metallo-ceramic involving pressure-less sintering (PLS) of elemental powders followed by spark plasma sintering (SPS) sintering of the crushed reaction product of the PLS product is described. High purity Cr2AlC was obtained for PLS 1400 degrees C for 1 h in argon. Depending on the ball milling conditions either intermediate coarse equiaxed Cr2AlC particles or intermediate small flake like Cr2AlC particles were obtained. SPS of the coarse powder resulted in high density bulk samples with a random texture. SPS of the fine powder resulted in high density bulk samples with a well-developed texture such that the (0001) planes are perpendicular to the compression direction. The hardness of fine-grained Cr2AlC bulk ceramic along different directions is both higher than that of coarse-grained Cr2AlC bulk ceramic. Due to its texture the fine-grained Cr2AlC bulk ceramic shows an anisotropic fracture behavior. (C) 2014 Elsevier Ltd. All rights reserved.