Nanostructured SiC prepared by ultra low temperature densification using amorphous/nano-crystalline bimodal Si-Al-C powder

摘要

Mechanical alloying and spark plasma sintering were used to fabricate dense and nanostructured SiC at 1525 degrees C under 40 MPa pressure. Round-shaped nanopowder (d(50): 108 nm) consisting of amorphous Si-Al-C and beta-SiC crystallites was prepared using high-energy ball-milling. Aluminum was homogeneously distributed in the Si-AlC powder. The addition of Al during the milling process caused the decrement in the 3C-SiC crystallinity and promoted the generation of stacking faults in 3C-SiC. Dense SiC with the grain size of 132 nm was fabricated after a two-step sintering at 1600-1550 degrees C. The Al content in the sintered SiC grain was more than 3 times higher than the reported values. Grain boundary diffusion and lattice diffusion were activated due to the high concentration of Al in the powder.