Silicon carbide hot pressing sintered by magnesium additive: microstructure and sintering mechanism

Silicon carbide was hot pressing sintered at 1300 ̊C/30 MPa by using magnesium additive. Microstructure and sintering mechanism are studied. Result shows that the hot pressing sintered sample composed of both α-SiC and β-SiC, indicating that no polytype transition has happened. Magnesium with stacking faults is located on the silicon carbide matrix as second phase particles. Dislocations and stacking defaults are initiated from grain boundaries and move toward the interior. Micropores locate on grain boundaries, substructure and triple grain junction, revealing a boundary diffusion mechanism. Long-range dislocations in grains and substructures in the lattice confirm a power-law creep mechanism.