Synthesis and characterization of Cr_2AlC ceramics prepared by spark plasma sintering

摘要

The investigation of bulk Cr_2AlC ceramic fabricated by Spark Plasma Sintering (SPS) from coarse powders (CAC10) and fine powders (NCAC10) in the temperature range of 1100-1400 ℃ was carried out. The XRD results indicate that Cr_2AlC, as major phase, always appears with minor and trace amount of Cr_7C_3 and Cr_2Al respectively in both NCAC10 and CAC10 samples and the amounts of later two phases decrease with increase in temperature. However, the Cr_2AlC phase content in NCAC10 is higher than that of CAC 10 sintered at the same temperature. The micrographs of back-scattered SEM show that grains with smaller size and pores with fewer amounts appear in SPSed NCAC10 in comparison to that of CAC10. As consequence, the higher hardness (5.6 GPa) of NCAC10 than that (3.9 GPa) of CAC10 was obtained. The patterns of XRD, microstructure and hardness of samples HPed at 1400 ℃ for the same composition were also presented for comparison.