The reaction mechanism for the low temperature synthesis of Cr2AlC under electronic field

The synthesis mechanism of Cr2AlC powder using Cr/Al/C and Cr/Al/Cr3C2 systems through pressureless spark plasma sintering was studied in the temperature range of 700-1200 degrees C under an argon atmosphere. The modified mold was applied in order to synthesize a large quantity powder without pressure, which synthesized 60 g of powder at a once. The synthesis temperature was strongly dependent on the starting composition. For Cr/Al/C system, Cr2AlC with a very small amount AlCr2 was synthesized at 1200 degrees C. For Cr/Al/Cr3C2 system, high purity Cr2AlC powder was synthesized at 1000 degrees C. The synthesis of Cr2AlC powder at low temperature was attributed to the combination of a current effect by spark plasma sintering and the introduction of milled Cr3C2 as carbon source. Transmission electron microscopy analysis indicated the dissolution of Cr3C2 in molten Al, the precipitation of needle-like Al4C3 grains and the formation of Cr2AlC in the liquid phase. (C) 2013 Elsevier B. V. All rights reserved.